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Interstate 40
Interstate 40
Interstate 40
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Interstate 40 marker
Interstate 40
Map
Route information
Length2,556.61 mi[1] (4,114.46 km)
ExistedAugust 14, 1957[2]–present
NHSEntire route
Major junctions
West end I-15 in Barstow, CA
Major intersections
East end US 117 / NC 132 in Wilmington, NC
Location
CountryUnited States
StatesCalifornia, Arizona, New Mexico, Texas, Oklahoma, Arkansas, Tennessee, North Carolina
Highway system

Interstate 40 (I-40) is a major east–west transcontinental Interstate Highway in the southeastern and southwestern portions of the United States. At a length of 2,556.61 miles (4,114.46 km), it is the third-longest Interstate Highway in the country, after I-90 and I-80. From west to east, it passes through California, Arizona, New Mexico, Texas, Oklahoma, Arkansas, Tennessee, and North Carolina. Its western terminus is at I-15 in Barstow, California, while its eastern terminus is at a concurrency with U.S. Route 117 (US 117) and North Carolina Highway 132 (NC 132) in Wilmington, North Carolina. Major cities served by the Interstate include Flagstaff, Arizona; Albuquerque, New Mexico; Amarillo, Texas; Oklahoma City, Oklahoma; Fort Smith and Little Rock in Arkansas; Memphis, Nashville, and Knoxville in Tennessee; and Asheville, Winston-Salem, Greensboro, Durham, Raleigh, and Wilmington in North Carolina.

I-40 begins in the Mojave Desert in California, and then proceeds through the Colorado Plateau in Arizona and the southern tip of the Rocky Mountains in New Mexico. It then traverses the Great Plains through the Texas Panhandle and Oklahoma, and passes south of the Ozarks in Arkansas. The freeway crosses the Appalachian Mountains in Tennessee and North Carolina, before terminating in the Atlantic Coastal Plain near the Atlantic Ocean.

Much of the western part of I-40, from Barstow to Oklahoma City, parallels or overlays the historic U.S. Route 66. East of Oklahoma City, the route generally parallels US 64 and US 70. I-40 was established by the Federal-Aid Highway Act of 1956, and the numbering was subsequently approved on August 14, 1957, along with most of the rest of the system. The eastern terminus was initially planned to be located at I-85 in Greensboro, but the Federal Highway Administration later approved extending the route to its current eastern terminus in Wilmington. As a result, this was the last segment of I-40 to be completed upon its dedication in 1990.

Route description

[edit]
Lengths
  mi[1] km
CA 154.61 248.82
AZ 359.48 578.53
NM 373.51 601.11
TX 177.10 285.01
OK 331.73 533.87
AR 284.69 458.16
TN 455.28 732.70
NC 420.21 676.26
Total 2,556.61 4,114.46

I-40 is the third-longest freeway in the United States, spanning 2,556.61 miles (4,114.46 km) across the southern half of the country. The longest stretch of the highway is in Tennessee, and the shortest is in California. The busiest stretch of I-40 is in Knoxville, concurrent with I-75, which has an annual average daily traffic volume of more than 210,000 vehicles.[3] The lowest traffic volumes are found on rural stretches in New Mexico, Texas, and Oklahoma, where the freeway carries fewer than 15,000 vehicles per day.[4][5][6]

California

[edit]
A sign at the start of I-40 in Barstow, California, showing the distance to the freeway's eastern terminus in Wilmington, North Carolina. This sign has been stolen several times.
Main article: Interstate 40 in California

I-40 in California crosses through the lightly populated northern part of the Inland Empire region of the state. Its western end is in Barstow, California. Known as the Needles Freeway, it heads east from Barstow across the Mojave Desert in San Bernardino County to Needles, before it crosses the Colorado River into Arizona southwest of Kingman. I-40 covers 155 miles (249 km) in California. Some signs show the control city for I-40 westbound to be Los Angeles, where drivers would follow I-15 south from its western terminus in Barstow. The highway is four lanes for the entirety of its length in the state.

A sign in California showing the distance to Wilmington, North Carolina, has been stolen several times.[7]

Arizona

[edit]
I-40 westbound heading toward Flagstaff
Main article: Interstate 40 in Arizona

I-40 is a main route to the South Rim of the Grand Canyon, with the exits leading into Grand Canyon National Park in Williams and Flagstaff. I-40 covers 359 miles (578 km) in Arizona. Just west of exit 190, west of Flagstaff, is its highest elevation along I-40 in the US, as the road crosses just over 7,330 feet (2,230 m) at the Arizona Divide near milepost 190. I-40 also passes through the Navajo Nation, the largest Indian reservation in the US. Like California's segment, the highway is four lanes for the entirety of its length in the state.

New Mexico

[edit]
Main article: Interstate 40 in New Mexico

I-40 covers 374 miles (602 km) in New Mexico. As in other states it parallels or overrides the post 1937 Route 66 route through the state. Notable cities along I-40 include Gallup, Grants, Albuquerque, Santa Rosa, and Tucumcari. I-40 also travels through several Indian reservations in the western half of the state. It reaches its highest point in the state of 7,275 feet (2,217 m) at the Continental Divide (Campbell Pass) in western New Mexico between Gallup and Grants. The last place that I-40 tops 7,000 feet (2,100 m) is at the head of Tijeras Canyon east of Albuquerque at approximately 7,040 feet (2,150 m).

Arizona, New Mexico, Texas, Oklahoma, and Arkansas are the five states where I-40 has a speed limit of 75 mph (121 km/h) instead of the 70 mph (110 km/h) limit in California, Tennessee, and North Carolina.[8][9]

Texas

[edit]
An at-grade intersection on I-40 in Texas, 2003
Main article: Interstate 40 in Texas

In the west Texas panhandle area, there are several ranch roads connected directly to the Interstate. The only major city in Texas that is directly served by I-40 is Amarillo, which connects with I-27 that runs south toward Lubbock. I-40 also connects to US 287 that runs southeast to Dallas–Fort Worth and US 87/US 287 north to Dumas and then on into Oklahoma. I-40 has only one welcome center in the state, which is located in Amarillo at the exit for Rick Husband Amarillo International Airport, serving both sides of the Interstate.

I-40 in Downtown Oklahoma City

Oklahoma

[edit]
Main article: Interstate 40 in Oklahoma

I-40 goes through the heart of the state, passing through many Oklahoma cities and towns, including Erick, Sayre, Elk City, Clinton, Weatherford, El Reno, Yukon, Oklahoma City, Del City, Midwest City, Shawnee, Okemah, Henryetta, Checotah, Sallisaw, and Roland. I-40 covers 331 miles (533 km) in Oklahoma.

In Downtown Oklahoma City, I-40 was rerouted one mile (1.6 km) south of its former alignment and a 10-lane (five in each direction) facility replaced the former I-40 Crosstown Bridge; the former I-40 alignment will be replaced with an urban boulevard currently designated as Oklahoma City Boulevard.

Arkansas

[edit]
The Hernando de Soto Bridge, where I-40 crosses the Mississippi River into Memphis
Main article: Interstate 40 in Arkansas

I-40 enters the west-central part of the state and runs for 285 miles (459 km) in Arkansas. The route passes through Van Buren, where it intersects the southbound I-540/US 71 to Fort Smith.[10] The route continues east to Alma to intersect I-49 north to Fayetteville, Arkansas. Running through the Ozark Mountains, I-40 serves Ozark, Clarksville, Russellville, Morrilton, and Conway. The route turns south after Conway and enters North Little Rock, which brings high volume interchanges with I-430, I-30/US 65/US 67/US 167, and I-440/Highway 440 (AR 440).[11] The Interstate continues east through Lonoke, Brinkley, and West Memphis on the eastside. I-40 briefly overlaps I-55 in West Memphis before it crosses the Mississippi River on the Hernando de Soto Bridge and enters Memphis, Tennessee.[12]

Tennessee

[edit]
Main article: Interstate 40 in Tennessee
I-40 in Nashville

The State of Tennessee has the longest segment of I-40 at 455 miles (732 km). The Interstate goes through all of the three Grand Divisions of Tennessee and its three largest cities: Memphis, Nashville, and Knoxville. Jackson, Lebanon, Cookeville, Crossville, and Newport are other notable cities through which I-40 passes. Before leaving the state, I-40 enters the Great Smoky Mountains toward North Carolina.

The section of I-40 which runs between Memphis and Nashville is often referred to as the Music Highway.[13] During reconstruction, a short section of I-40 through downtown Knoxville near the central Malfunction Junction was completely closed to traffic from May 1, 2008, and not reopened until June 12, 2009, with all traffic redirected via I-640, the northern bypass route. The redesigned section now has additional lanes in each direction, is less congested, and has fewer accidents.[14][15]

North Carolina

[edit]
A sign displaying the distance to Barstow near Wilmington. This sign is no longer posted by NCDOT due to the frequency of its theft.[16]
The beginning of I-40 west, near Wilmington
Main article: Interstate 40 in North Carolina

In North Carolina, I-40 travels 420 miles (680 km). It enters the state as a winding mountain freeway through the Great Smoky Mountains, which frequently closes due to landslides and weather-related problems. It enters the state on a mostly north–south alignment, turning to a more east–west alignment upon merging with US 74 at the eastern terminus of the Great Smoky Mountains Expressway. From there, the highway passes through Asheville, Hickory, and Statesville before reaching the Piedmont Triad. Just east of the Triad City of Greensboro, North Carolina, it merges with I-85, and the two roads split again just west of the Research Triangle area, passing through Durham and Raleigh. From the Triangle to its eastern terminus in Wilmington, it once again takes a more north–south alignment.

A standard distance sign existed near the start of the westbound section of I-40 in Wilmington that indicated the distance to Barstow, California, as 2,554 miles (4,110 km). In 2009, NCDOT said it would not be replaced after frequent thefts.[17]

History

[edit]

Predecessors and planning

[edit]
A monument to Beale's Wagon Road in Kingman, Arizona

During the colonial and westward expansion eras, a number of Native American trails existed within the vicinity of what is now Interstate 40. In 1857, an expedition led by Lt. Edward Fitzgerald Beale was tasked with establishing a trade route along the 35th parallel north from Fort Smith, Arkansas, to Los Angeles. This route, which became known as Beale's Wagon Road, was constructed by a team of about 100 men and 22 camels led by Beale. Completed in 1859, it is generally considered the first federal highway in the Southwestern United States.[18]

In the early 20th century, a number of auto trails were established by private organizations to aid motorists in traveling between major cities. Among these was the National Old Trails Road, which roughly followed the western part of present-day I-40 to Albuquerque, and the Lee Highway, which followed much of the eastern portion of the route.[19] When the state governments established the United States Numbered Highway System in 1926, two of these most important highways, US 66 and US 70 were established within the present-day I-40 corridor.[20]

US 66, which followed the route from its western terminus to Oklahoma City, became arguably the most famous highway in the United States and has been recognized multiple times in popular culture.[21] US 70, which roughly follows the remainder of the Interstate, was also one of the most important highways for east−west travelers, and was considered part of the "Broadway of America" highway between California and New York.[22]

An east−west trans-continental freeway to serve the south-central United States was proposed in multiple plans throughout the 1930s and 1940s for what later became the Interstate Highway System.[23] The general alignment for the highway that became I-40 was included in a plan released on August 2, 1947, by the Public Roads Administration of the now-defunct Federal Works Agency.[24] The Interstate was officially authorized between Barstow and Greensboro by the Federal-Aid Highway Act of 1956, which created the Interstate Highway System. The numbering was subsequently approved by the American Association of State Highway Officials (AASHO) on August 14, 1957, along with most of the system.[2]

In 1957, the California Department of Highways, the predecessor agency to the California Department of Transportation (Caltrans), proposed that the route be renumbered to I-30 instead because of the already existing US 40 in the state. This route was decommissioned in the state in 1964 as a part of a major revamping of California's overall highway numbering system.[25] The California state government also submitted State Route 58 (SR 58) between Barstow and Bakersfield for I-40 extension potential in 1956 and 1968, but both of these requests were rejected.[26]

From 1963 to 1966, the US government considered a plan, part of Project Plowshare, to use atomic bombs to excavate a path for I-40 through California. The project was canceled largely due to the cost of developing the explosives and due to the unavailability of a "clean bomb".[27]

Construction

[edit]

The first sections of I-40 reused freeways that had been constructed prior to the Interstate Highway System or were under construction at the time of the authorization of the system. The first stretch in Tennessee reused a short freeway in Knoxville called the Magnolia Avenue Expressway, which was opened in two segments in 1952 and 1955. The first stretches in North Carolina were a short controlled-access section of US 421 in Winston-Salem, and from Kernersville, constructed between 1955 and 1958. By 1957, most states had begun construction on the first sections of I-40.[citation needed] The first construction project specifically for I-40 in 1958 was a section along the Pigeon River in Western North Carolina.[28] The stretch between Memphis and Nashville, completed on July 24, 1966, was the first major stretch of interstate highway completed in Tennessee.[29]

On June 30, 1972, the final stretch of I-40 entirely within Arkansas, located between Clarksville and Ozark was opened;[30] the last section to open in the state was the Hernando de Soto Bridge, which opened on August 2, 1973.[31][32] The last segment in California to be completed was a short stretch in Needles, opened on August 13, 1973.[33][34] The last original planned stretch of the highway in Tennessee, located east of Knoxville, was partially opened on December 20, 1974,[35] and fully opened on September 12, 1975.[36] The last section of I-40 in Oklahoma, a 17-mile (27 km) stretch near Erick near the western end of the state, opened on June 2, 1975.[37][38]

In 1971, the North Carolina State Highway Commission approved a plan to extend I-40 from Research Triangle Park to I-95, a distance of 41 miles (66 km), at a cost of $75 million (equivalent to $443.71 million in 2024[39]). Most of the highway would be four lanes, though six lanes were likely near Raleigh, where I-40 would extend the Beltline. Several routes were being considered, but, at the time, the most likely route would have ended north of Smithfield.[40] When the last portion of I-40, connecting Wilmington to Raleigh, was dedicated on June 29, 1990, CBS journalist Charles Kuralt stated:

Thanks to the Interstate Highway System, it is now possible to travel from coast to coast without seeing anything.[41][28]

Controversies

[edit]

In Memphis, I-40 was originally planned to pass through the city's Overton Park, a 342-acre (138 ha) public park. Following a public announcement of the routing, a group of community activists opposed to the routing founded an organization called Citizens to Preserve Overton Park in 1957, and collected 10,000 signatures in their support.[42] After Secretary of Transportation John Volpe authorized the state to solicit bids for the construction of the Interstate through the park in 1969, the organization filed a lawsuit, which culminated in the landmark Supreme Court ruling of Citizens to Preserve Overton Park v. Volpe in 1971, which ruled that the state highway department had not adequately explored alternative routes for the interstate.[43] This case is considered to have established the modern process of judicial review of infrastructural projects, and eventually resulted in the state rerouting the alignment of I-40 through the park onto a section of I-240 in 1981.[42][44]

Major projects

[edit]

Between May 1980 and March 1982, a major project was conducted on I-40 in Knoxville that widened the route, eliminated several interchanges, added frontage roads, and reconstructed the congestion-prone cloverleaf interchange with I-75, which had earned the nickname "Malfunction Junction", into a three-level stack interchange.[45][46] This was conducted as part of a larger $250 million (equivalent to $686 million in 2024[39]) road improvement project in the Knoxville area in preparation for the 1982 World's Fair.[47][48]

Originally, I-40 was constructed through downtown Winston-Salem, and it continued to follow that route until a new urban bypass route was built. After the bypass was completed around 1992, I-40 was relocated to the new freeway, that went through the urban areas of the city while avoiding the congested Downtown. The old highway was then redesignated as Interstate 40 Business (I-40 Bus.), establishing a business route that was actually a freeway for its entire length, a rarity among business routes. Following a reconstruction, the expressway was renamed Salem Parkway and redesignated as part of US 421.

The "Big I" interchange in Albuquerque between I-40 and I-25 was reconstructed between 2000 and 2002 in a project that eliminated left-hand entrance ramps and added lanes. This project was given an honorable mention by the United States Department of Transportation and the FHWA for excellence in urban highway design in 2002.[49]

The Oklahoma City Crosstown Expressway was relocated and replaced with a new wider alignment in two phases between May 2002 and October 2012. The old alignment was replaced with Oklahoma City Boulevard, and at-grade thoroughfare.[50]

In Memphis, the cancellation of the Overton Park stretch of I-240, along with increased traffic volumes and safety hazards, rendered both interchanges with I-240 unable to effectively handle unplanned traffic patterns, thus necessitating their reconstruction. This was accomplished in three phases between January 2001 and December 2016.[51][52][53][54]

A $203.7 million two-phase project dubbed "SmartFix 40" resulted in a complete closure of a short stretch of I-40 through Knoxville between May 1, 2008, and June 12, 2009.[55] This was done in order to accelerate the construction timeline, and during this time, through traffic was required to use I-640.[56] Both phases of the project won an America's Transportation Award from AASHTO in 2008 and 2010, respectively.[57][58]

Geological difficulties

[edit]

Landslides are common in the Pigeon River Gorge section along the Tennessee and North Carolina border. Here, the roadway was cut into the slopes of several steep mountains. Accidents on the winding road are also common especially during bad weather. On October 25, 2009, I-40 was closed at the North Carolina and Tennessee border due to a landslide at milemarker 2.6 just east of the Tennessee state line. All traffic was detoured via I-26 and I-81, and non-heavy-load traffic via US 25 and US 70.[59] The roadway was reopened on April 25, 2010, with some remaining limitations on westbound traffic.[60]

Major incidents

[edit]
The collapsed section of the I-40 bridge, May 31, 2002

On December 23, 1988, a tanker truck hauling liquefied propane overturned on a ramp in the interchange between I-40 and I-240 in the Midtown neighborhood of Memphis, rupturing a small hole in the front of the tank.[61][62] The leaking gas ignited in a massive fireball, and the tank was propelled 125 yards (114 m) from the crash site into a nearby duplex apartment.[63] The incident killed six motorists and three occupants of nearby structures, and provided momentum for the eventual reconstruction of the interchange.[64][54]

The I-40 bridge disaster occurred on May 26, 2002, when a barge collided with a bridge foundation member near Webbers Falls, Oklahoma, causing a 580-foot (180 m) section of the I-40 bridge to plunge into the Arkansas River. Automobiles and semitrailers fell into the water, killing 14 people.

On May 11, 2021, the Hernando de Soto Bridge carrying I-40 over the Mississippi River was closed when inspectors discovered a crack on a tie girder.[65] A subsequent investigation revealed that the crack had existed since at least May 2019, and reports later surfaced that the crack had likely existed since August 2016.[66][67] An emergency contract to repair the beam was awarded six days after the closure,[68][69] and the bridge reopened on July 31, 2021, to eastbound traffic,[70] and to westbound traffic on August 2, 2021.[71]

The highway was badly damaged during Hurricane Helene in September 2024, with the road closed in multiple locations across western North Carolina due to landslides.[72] The worst damage was seen near North Carolina's border with Tennessee, where a large portion of the highway was washed into the Pigeon River following a mudslide, resulting in it being indefinitely closed in both directions.[73][74] On November 5, it was announced that the highway could reopen as early as the beginning of 2025.[75]

Major junctions

[edit]
California
I-15 in Barstow
US 95 west-northwest of Needles. The highways travel concurrently to Needles.
Arizona
Future I-11 / US 93 in Kingman. The highways travel concurrently to east-northeast of Kingman.
I-17 in Flagstaff
US 89 / US 180 in Flagstaff. I-40/US 180 travels concurrently to Holbrook.
US 191 in Chambers. The highways travel concurrently to Sanders.
New Mexico
US 491 in Gallup
I-25 / US 85 in Albuquerque
US 285 in Clines Corners
US 84 west-northwest of Santa Rosa. The highways travel concurrently to Santa Rosa.
US 54 in Santa Rosa. The highways travel concurrently to Tucumcari.
Texas
US 385 in Vega
I-27 / US 60 / US 87 / US 287 in Amarillo. I-40/US 287 travels concurrently through Amarillo.
US 83 in Shamrock
Oklahoma
US 283 in Sayre
US 183 in Clinton
US 281 in Hinton
US 270 west of El Reno. The highways travel concurrently to northwest of Shawnee.
US 81 in El Reno
I-44 in Oklahoma City
I-35 / I-235 / US 62 / US 77 in Oklahoma City. I-35/I-40/US 62 travels concurrently through Oklahoma City.
I-240 in Oklahoma City
US 177 / US 270 northwest of Shawnee
US 377 south-southeast of Prague
US 62 in Okemah. The highways travel concurrently to Henryetta.
US 75 northeast of Clearview. The highways travel concurrently to Henryetta.
US 69 southwest of Checotah
US 266 in Warner
US 59 in Sallisaw
US 64 in Sallisaw
US 64 in Roland
Arkansas
I-540 / US 71 in Van Buren. I-40/US 71 travels concurrently to Alma.
I-49 in Alma
US 64 in Clarksville
US 64 in Lamar
US 64 in London
US 65 in Conway. The highways travel concurrently to North Little Rock.
US 64 in Conway
I-430 in North Little Rock
I-30 / I-57 / US 65 / US 67 / US 167 in North Little Rock. I-40/US 67/US 167 travels concurrently through North Little Rock.
I-440 in North Little Rock
US 63 in Hazen. The highways travel concurrently to Brinkley.
US 49 in Brinkley
US 79 south of Jennette. The highways travel concurrently to West Memphis.
I-55 / US 61 / US 64 in West Memphis. The highways travel concurrently through West Memphis.
Tennessee
US 51 in Memphis
I-69 / I-240 in Memphis. I-40/I-69 travels concurrently through Memphis.
US 64 / US 70 / US 79 in Memphis
US 64 on the Memphis–Bartlett city line
I-269 in Arlington
US 70 east of Brownsville
US 412 in Jackson. The highways travel concurrently to northeast of Jackson.
US 45 in Jackson
US 70 / US 412 northeast of Jackson
US 641 southeast of Holladay
I-840 southeast of Burns
US 70S in Nashville
US 70 in Nashville
I-440 in Nashville
I-65 in Nashville. The highways travel concurrently through Nashville.
US 70 in Nashville
US 70 / US 70S / US 431 in Nashville
US 31A / US 41A in Nashville
I-24 in Nashville. The highways travel concurrently through Nashville.
I-840 in Lebanon
US 231 in Lebanon
US 70 in Lebanon
US 70N in Cookeville
US 70N in Monterey
US 127 in Crossville
US 27 in Harriman
US 321 in Lenoir City
I-75 west of Farragut. The highways travel concurrently to Knoxville.
I-140 in Knoxville
US 11 / US 70 in Knoxville
I-75 / I-640 in Knoxville
US 129 in Knoxville
I-275 in Knoxville
US 441 in Knoxville
US 11W in Knoxville
I-640 / US 25W in Knoxville. I-40/US 25W travels concurrently through Knoxville.
US 11E / US 25W / US 70 in Knoxville
US 25W / US 70 west of Dandridge
I-81 north-northeast of Dandridge
US 25W / US 70 / US 411 in Newport
US 321 in Newport
North Carolina
US 276 in Cove Creek
US 74 north-northwest of Clyde. The highways travel concurrently to Asheville.
US 19 / US 23 in Asheville
I-26 / I-240 / US 74 in Asheville
US 25 in Asheville
I-240 in Asheville
US 70 in Black Mountain. The highways travel concurrently to southwest of Old Fort.
US 221 southeast of West Marion
US 64 in Morganton
US 321 in Hickory
US 64 in Statesville
US 21 in Statesville
I-77 in Statesville
US 64 in Statesville
US 64 east-northeast of Statesville
US 64 west-northwest of Mocksville
US 601 in Mocksville
US 421 in Winston-Salem
US 158 in Winston-Salem
US 52 / I-285 in Winston-Salem
I-74 in Winston-Salem
US 421 west of Greensboro. The highways travel concurrently to Greensboro.
I-73 / US 421 / I-840 in Greensboro
US 220 in Greensboro. The highways travel concurrently through Greensboro.
US 29 / US 70 in Greensboro. The highways travel concurrently through Greensboro.
I-85 / I-840 / I-785 in Greensboro. I-40/I-85 travels concurrently to southwest of Hillsborough.
US 15 / US 501 in Durham
I-885 in Durham
I-540 in Durham
I-440 / US 1 / US 64 in Raleigh. I-40/US 64 travels concurrently through Raleigh.
US 70 / US 401 in Raleigh
I-87 / I-440 / US 64 in Raleigh
US 70 in Garner. The highways travel concurrently to west-southwest of Clayton.
I-42 / US 70 near Clayton.
I-95 in Benson
US 701 south-southeast of Newton Grove
US 117 south-southeast of Warsaw
US 117 east-southeast of Willard
I-140 in Murraysville
US 117 on the Kings Grant–Murraysville CDP line

[76]

Auxiliary routes

[edit]

In Oklahoma City, the designation I-440 had been given to a stretch of Interstate Highway from I-240 to US 66. It was a part of Grand Boulevard that had been built in compliance with Interstate Highway standards. In 1982, as part of Oklahoma's "Diamond Jubilee", I-44's western terminus was moved from the I-35/I-44 junction to the Texas–Oklahoma state line via the Belle Isle Freeway (connecting I-440 with I-35); I-440, the H. E. Bailey Turnpike; and the turnpike connector road on the eastern edge of Lawton, Oklahoma. The I-440 number was dropped at the time.

Business routes

[edit]
See also: Business routes of Interstate 40

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Interstate 40

View on Grokipedia
from Grokipedia
Interstate 40 (I-40) is a major east–west transcontinental Interstate Highway in the United States, extending 2,555 miles (4,112 km) from its western terminus at in , to its eastern terminus at U.S. Route 117 in . The route traverses eight states—, , , , , , , and —passing through diverse terrains including expanses, , and the valley. Authorized under the and numbered in 1957, I-40 largely parallels historic in the west and facilitates freight and passenger transport across key economic hubs such as Albuquerque, , , Memphis, and Nashville. Despite its role in enhancing national connectivity and commerce, the highway has faced engineering challenges from geological instability, notably rockslides in mountainous sections, and records high traffic fatalities, with 270 deaths reported in 2020 alone, attributed to factors like excessive speeds and congestion.

Overview

Route Summary and Endpoints

Interstate 40 (I-40) is a transcontinental east-west Interstate Highway in the United States with its western terminus at an interchange with in . The route extends eastward across the , paralleling portions of the historic , before crossing the into . The highway traverses eight states—California, Arizona, New Mexico, Texas, Oklahoma, Arkansas, Tennessee, and North Carolina—for a total length of 2,555 miles (4,112 km), making it the third-longest Interstate Highway after I-90 and I-80. In its eastern terminus, I-40 ends at a junction with U.S. Route 117 and North Carolina Highway 132 in Wilmington, North Carolina, near the Atlantic Coast. I-40 serves as a vital corridor for freight and passenger traffic, connecting major metropolitan areas including ; Oklahoma City, Oklahoma; Memphis and ; and providing access to the Port of Wilmington. Its path avoids the by routing south of them, facilitating more direct east-west travel compared to northern Interstates.

Length, Traffic, and Design Standards

Interstate 40 measures 2,555.10 miles (4,112.03 km) in total length, making it one of the longest routes in the Interstate Highway System and traversing eight states from Barstow, California, to Wilmington, North Carolina. This east-west corridor serves as a primary freight and passenger artery, with mileage distributed unevenly across states: approximately 157 miles in California, 359 miles in Arizona, 368 miles in New Mexico, 177 miles in Texas, 331 miles in Oklahoma, 285 miles in Arkansas, and longer segments in Tennessee and North Carolina. Annual average daily traffic (AADT) on I-40 fluctuates widely due to its path through diverse terrains and population centers, with rural western sections often below 15,000 vehicles per day and peak urban volumes exceeding 200,000. In , AADT near Albuquerque averages 202,000 vehicles, including 12% trucks, while remote stretches to the east drop to 12,700 vehicles with 10% truck traffic. Oklahoma's segments through routinely surpass 100,000 vehicles daily, supported by state monitoring data, whereas Arizona's rural I-40 near Flagstaff records around 30,000-40,000 vehicles. Freight dominates in the central states, with truck percentages reaching 15-20% in and corridors, reflecting I-40's role in national logistics networks. As part of the Interstate System, I-40 conforms to standards mandating full via interchanges, minimum four travel lanes (expanding to six or more in urban zones), 12-foot lane widths, and 10-foot shoulders in rural areas. Design speeds target 70 mph in flat rural terrain but reduce to 50-65 mph in mountainous sections like Arizona's Black Canyon or Tennessee's Walden Ridge, where grades and curves necessitate features such as escape ramps and signage. Posted speed limits align with these designs at 70 mph across most rural portions in states including , , and , with select increases to 75 mph in low-density areas of and ; urban and construction zones enforce reductions to 35-65 mph to mitigate congestion and hazards. Recent modifications, such as narrowed lanes during repairs in North Carolina's Pigeon River Gorge, temporarily impose 35 mph limits and barriers to maintain flow amid geometric constraints.

Route Description

California Segment

Interstate 40's California segment constitutes its western terminus, beginning at a diamond interchange with in Barstow, San Bernardino County. This 155-mile (249 km) portion extends eastward entirely within San Bernardino County through the , a remote and arid region with minimal population centers. The highway maintains a predominantly rural character, serving as a key east-west corridor for freight and long-distance travel, with design standards adhering to Interstate guidelines including divided lanes, controlled access, and grade-separated interchanges. From Barstow, I-40 proceeds east, initially passing near industrial areas before entering open desert terrain. Key intermediate exits include those for Daggett at milepost 7 (Old Highway 58), Newberry Springs at mile 12 (Newberry Road), and at mile 48 (National Trails Highway, former alignment). Further east, the route traverses even sparser areas past Amboy Road (mile 72) and Road (mile 100), with occasional services at ghost towns and tied to historic travel corridors. The highway largely parallels the original alignment of , incorporating segments of the and reflecting mid-20th-century realignments for higher-speed traffic. Approaching its eastern end, I-40 reaches Needles, where exits serve local access via North Needles Highway (mile 141), Hall Drive (mile 144), and (mile 148). The segment terminates at the Arizona state line after crossing the via a bridge prone to structural wear from heavy loads and environmental exposure. Caltrans is replacing this bridge to address deck deterioration and enhance load capacity, with construction aimed at maintaining seismic resilience and traffic flow. Known locally as the Needles Freeway, the California portion experiences moderate truck traffic but sees seasonal increases from tourism along adjacent Route 66 byways.

Arizona Segment

Interstate 40 (I-40) in spans approximately 359 miles (578 km) across the northern part of the state, entering from at the Colorado River Bridge near Topock and exiting into near Lupton. The route generally parallels the historic and the BNSF railroad line, traversing diverse terrain from the low-elevation in the west to forested plateaus near Flagstaff and open high plains toward the east. It serves as a key east-west freight corridor, designated by the Arizona Department of Transportation (ADOT) as a strategic and part of the National Primary Freight Network. From the California state line (milepost 0), I-40 crosses the and proceeds east through , intersecting State Route 95 (SR 95) at milepost 11 near Topock. The highway then climbs gradually into the Hualapai Hills before reaching Kingman at mileposts 48–55, where it meets (US 93), a major north-south corridor linking Phoenix to . East of Kingman, the route passes through rural areas with interchanges at Blake Ranch Road (milepost 66) and near Seligman and Ash Fork, before ascending into the toward Williams. The western segment concludes at the I-17 interchange in Flagstaff (milepost 196), a critical junction connecting to Phoenix. Elevations reach around 6,950 feet (2,120 m) in areas east of Flagstaff, where the highway winds through ponderosa pine forests before descending to the Valley. Continuing east for about 163 miles (262 km), I-40 passes Winslow (interchanges at mileposts 246–258, including SR 87), Holbrook (mileposts 286–290), and Joseph City, with business routes serving these towns. The eastern end features interchanges near Chambers and Houck before crossing into at milepost 359 near Lupton and the community of Window Rock. The route includes 42 interchanges in the western half alone, with ongoing improvements such as pavement rehabilitation and rockfall mitigation near Flagstaff. Traffic volumes vary, reaching up to 37,769 vehicles per day in segments east of Flagstaff, reflecting its role in regional commerce. Business loops of I-40 exist in Kingman, Seligman, Ash Fork, Williams, Flagstaff, Winslow, Joseph City, and Holbrook, preserving access to historic alignments.

New Mexico Segment

Interstate 40 traverses 373.53 miles (601.14 km) across , entering from near and exiting into near Glenrio, functioning as the state's principal east-west artery and a key national freight corridor. The highway largely overlays the alignment of historic , facilitating travel through diverse terrain including high desert plateaus, the Continental Divide, and open plains. From the Arizona state line, I-40 crosses the Continental Divide at elevation 7,275 feet (2,218 m) near milepost 15, followed by the Rest Area. It reaches Gallup in McKinley County, intersecting at exit 22, a primary access for the . Eastward, the route passes through rural areas and the Cibola National Forest, serving Grants in Cibola County via interchanges with New Mexico Route 53 (exits 81–85), before approaching Albuquerque from the west through lands. In Albuquerque, I-40 forms the base of the Big I, a complex with Interstate 25 at exits 159A–163, handling over 200,000 vehicles daily and reconstructed in phases during the early 2000s to address capacity constraints from its original 1966 design. The segment through the metro area includes urban service roads and connections to local arterials like New Mexico Route 45. East of the city, I-40 ascends Tijeras Canyon briefly before descending into the Estancia Valley, passing Moriarty and intersecting at Clines Corners (exit 218), a junction for traffic to Santa Fe. Continuing east, the highway crosses ranchlands to Santa Rosa in Guadalupe County, where it meets U.S. Routes 54 and 84 near exit 275, then proceeds to Tucumcari in Quay County, intersecting (exits 333–343) amid commercial development. The final stretch parallels River valley to the Texas line at milepost 373.53 near mile marker 356. Recent NMDOT studies, including corridor assessments from the line to Albuquerque completed in 2022, identify needs for lane additions, bridge upgrades, and safety enhancements due to high volumes exceeding 20% of . Construction of I-40 in commenced in the late 1950s following the , with major segments like the Big I opening by 1966 amid challenges from mountainous terrain and arroyo crossings requiring extensive grading and bridging.

Texas Segment (Panhandle)

Interstate 40 enters Texas from New Mexico at the state line west of the unincorporated community of Glenrio in Deaf Smith County, marking the start of its 177-mile (285 km) traversal of the Texas Panhandle. The highway proceeds eastward through flat, rural High Plains terrain, crossing into Oldham County and serving the small town of Vega at exit 35, where it intersects U.S. Route 385. Frontage roads and business routes parallel much of the corridor, reflecting its origins paralleling the historic U.S. Route 66 alignment. Approaching Potter County, I-40 reaches Amarillo, the economic hub of the Panhandle with a population exceeding 200,000 as of the 2020 census. Here, at exit 70, it junctions with , a 124-mile extending to Lubbock and connecting to the state's primary north-south corridor along former U.S. 87 and 287 alignments. The freeway bisects the city, providing access to industrial areas, the Amarillo Travel Information Center at mile marker 76, and local services via business loop routes; traffic volumes peak near 100,000 vehicles per day in urban sections. East of Amarillo, I-40 continues through Carson, Gray, Donley, and Wheeler counties, passing rural communities like Groom (home to the Leaning Water Tower landmark) and before reaching at exit 163. In , it intersects U.S. Routes 83 and 287, facilitating connections to Childress and Wichita Falls southward. The segment concludes at the Oklahoma state line east of , near the of Texola, maintaining four lanes throughout with occasional passing lanes in less populated stretches. The route's design adheres to Interstate standards, featuring grade-separated interchanges and minimal at-grade crossings, though it parallels active rail lines in places like Wheeler .

Oklahoma Segment

Interstate 40 spans 331 miles (533 km) across Oklahoma, entering from Texas in Beckham County near Texola and exiting into Arkansas in Sequoyah County near Roland. The route generally follows a straight east-west path through the state's southern tier, serving as a primary corridor for freight and passenger traffic between the Great Plains and the Ozarks. From the state line, I-40 proceeds eastward through rural Beckham County, with initial exits serving Texola (exit 1) and Erick (exits 7–11, including Oklahoma State Highway 30). It crosses into Roger Mills and Custer counties, passing Sayre (exits 14–15) and Elk City (exits 26–32, junction with U.S. Route 283), where a facilitates traffic flow at State Highway 6. Continuing east, the highway traverses (exits 38–42) and Weatherford (exits 60–62) in Custer and Blaine counties, then enters Canadian County near El Reno (exits 108–118), site of a new interchange with Radio Road completed to enhance local access. In the , I-40 forms a key segment of the urban freeway network, intersecting at exits 127–128 (H.E. Bailey Turnpike), Interstate 240 at exit 125, and at exits 145–153, where it briefly parallels the latter before diverging eastward. The route cuts through via the crosstown alignment, with exits for major arterials like (exit 148) and providing connectivity to the Kilpatrick Turnpike (exit 138) north of the city. Eastbound from the metro area in Oklahoma County, I-40 serves suburban communities including Harrah (exit 166) and serves in Pottawatomie County (exits 173–185, junction with U.S. Route 177). Further east, the highway passes through Lincoln County near Chandler (exits 200–205) and (exits 218–220), then enters the more rolling terrain of eastern Oklahoma. In Okfuskee and Okmulgee counties, it bypasses Okemah (exits 231–233) and Henryetta (exits 240–244, near ), followed by McIntosh County communities like Checotah (exits 264–265). The final segment in Sequoyah County includes Sallisaw (exits 308–311, junction with ) before terminating at the Arkansas line near exit 330 (State Highway 64D). Throughout its length, I-40 maintains four lanes divided with periodic widening to six lanes in urban zones, adhering to Interstate standards for high-volume travel.

Arkansas Segment

Interstate 40 enters Arkansas from at mile marker 0 near Dora, just north of the , and extends 284.7 miles eastward to the state line, crossing the via the into Memphis. The route primarily follows the for the first approximately 100 miles, transitioning to more varied terrain including crossings of the Petit Jean River and Lake Dardanelle before reaching the flatter Delta region and ascending Crowley’s Ridge east of Forrest City. From the state line, I-40 proceeds through Van Buren, where it intersects Interstate 540, providing access to Fort Smith. Continuing east, it passes Alma and connects with , which heads north toward Fayetteville. The highway then reaches Clarksville before entering Russellville, site of the power plant, and continues via Morrilton to Conway. In the Little Rock metropolitan area, I-40 serves North Little Rock with major interchanges including Interstate 430 to the south, Interstate 30/U.S. Highways 65, 67, and 167 eastward toward proper, and Interstate 440 southeastward. East of the capital region, the route passes Jacksonville and Cabot en route to Forrest City, then enters West Memphis, where it meets twice before terminating at the , opened in August 1973 as part of the full Arkansas segment's completion that year.

Tennessee Segment

Interstate 40 enters Tennessee from Arkansas across the , a tied-arch structure spanning the into Memphis. The bridge, completed in 1973, carries six lanes of eastbound and westbound traffic connecting Memphis with . In Memphis, I-40 interchanges with near downtown and parallels the southern edge of the city before merging with the I-240 loop, providing access to suburban areas and the via State Route 385. East of Memphis, I-40 traverses rural West Tennessee, passing through Fayette and Madison counties with interchanges at State Routes 196 and 100, before reaching Jackson where it meets U.S. Route 45. The highway continues through rolling terrain, crossing the near Savannah in Hardin County via a multi-span bridge. Approaching Middle Tennessee, I-40 enters the , intersecting west of downtown Nashville in a directional that facilitates heavy commuter traffic. In Nashville, I-40 serves as a key artery through the urban core, crossing the on the Lyle H. Fulton Memorial Bridge before connecting to southeast of the city center and Interstate 440, a short auxiliary route bypassing . East of Nashville, the route passes near and Cookeville, interchanging with State Route 111 and , amid increasing elevation toward the . The segment totals 455 miles (732 km), traversing 20 counties and serving as the state's primary east-west corridor. Entering , I-40 climbs into the Appalachian foothills near Crossville, interchanging with , before reaching Knoxville. In Knoxville, it forms a complex series of junctions with Interstate 75 and Interstate 640, including the I-40/I-75 interchange west of the city that handles significant freight and tourist volume toward the . The route then parallels the briefly before ascending through the Pigeon River Gorge, a steep, winding section prone to landslides and closures, toward the state line near Newport. Throughout its path, I-40 maintains a design speed of 70 mph (113 km/h) in rural areas, with capacity expansions ongoing in urban corridors to address congestion.

North Carolina Segment

Interstate 40 enters from in Haywood County via the Pigeon River Gorge, a narrow, winding corridor through the that experienced severe flooding and erosion damage from Hurricane Helene in September 2024, resulting in closure of both directions until partial reopening under restricted conditions in February 2025 with ongoing reconstruction efforts. The route descends eastward into Buncombe County, reaching Asheville, where it intersects at exits 46A-B and overlaps briefly with Interstate 240 to bypass the city center, providing access to downtown via exits along the loop. East of Asheville, I-40 continues through McDowell, Burke, and Catawba counties, passing near Old Fort and Marion before serving with connections to and U.S. Route 70. In Iredell County, the highway reaches Statesville and interchanges with at exits 152A-B, a major north-south route linking to Charlotte southward. Further east in Davie and Forsyth counties, I-40 skirts north of Winston-Salem, intersecting near Clemmons and providing access to the city via Business I-40 spurs. Entering Guilford County, I-40 passes through Greensboro, intersecting at exit 212 and , with service to the city's commercial districts via exits like Wendover Avenue (U.S. 70). The route then proceeds into Alamance County near Burlington before briefly overlapping Interstate 85 near Mebane in a concurrency eastward through Orange and Durham counties, serving the area including Chapel Hill and Durham with connections to U.S. Route 15/501. In Wake County, I-40 enters the Raleigh metropolitan area, intersecting Interstate 440 at exit 289 and /64, with widening projects completed in sections from Raleigh to Clayton adding lanes for increased traffic volume. Southeastward through Johnston, , and Pender counties, the highway traverses rural terrain, passing near Smithfield and Wallace with interchanges for state routes like Highway 50. Finally, in New Hanover County, I-40 reaches Wilmington, terminating at a junction with U.S. Route 117 and Highway 132 near the port city after approximately 420 miles across the state.

History

Pre-Interstate Predecessors

Prior to the construction of Interstate 40 (I-40), its corridor primarily followed segments of the U.S. Numbered Highway System established in November 1925 and commissioned in 1926 by the American Association of State Highway Officials (AASHO). In the western states from California to Oklahoma, the route superseded much of U.S. Route 66 (US 66), a 2,448-mile highway designated on November 11, 1926, that connected Chicago, Illinois, to Santa Monica, California, and facilitated migration, commerce, and tourism during the Dust Bowl era and post-World War II boom. US 66, often paved with concrete and asphalt between 1926 and the 1940s, carried up to 10,000 vehicles daily in peak sections by the 1950s but suffered from narrow lanes, frequent intersections, and inadequate maintenance, prompting its incremental replacement by interstates. I-40 absorbed alignments of US 66 starting from Barstow, California, eastward through the Mojave Desert, across Arizona's Painted Desert, New Mexico's Continental Divide, the Texas Panhandle, and into Oklahoma, where bypasses around cities like Albuquerque (opened 1950s–1960s) and Amarillo prefigured interstate standards. East of Oklahoma City, I-40's path paralleled U.S. Route 70 (US 70), another 1926-commissioned highway spanning approximately 2,381 miles from , to Atlantic, North Carolina, serving as a key east-west artery through the , crossings, and Appalachian foothills. US 70, upgraded with divided sections and bridges in –, handled freight and passenger traffic but faced congestion in urban areas like and Memphis, where I-40 construction from the late onward either upgraded or bypassed these alignments to achieve 70 mph design speeds and full . In , , and , segments of US 70—including the 1930 over the —were integrated or realigned for I-40, reflecting federal priorities under the 1944 Interstate Highway planning that prioritized existing high-volume corridors. Earlier precursors included 19th-century wagon roads and railroads influencing alignments, such as California's (1912 overlaying parts of US 66) and Arizona's Beale Wagon Road (1857 military survey route from Fort Smith to ), which provided foundational grading and surveys later exploited for highway paving. These pre-1926 paths, often unpaved dirt or gravel handling 100–500 vehicles daily, evolved through state aid programs post-1916 Federal Aid Road Act, but lacked uniformity until the U.S. system standardized signage and numbering. By the 1956 Federal-Aid Highway Act, an estimated 80% of I-40's mileage utilized upgraded predecessor rights-of-way, minimizing new land acquisition while addressing pre-interstate deficiencies like seasonal flooding and grade crossings.

Planning and Federal Designation

The , enacted on June 29, 1956, authorized the construction of the National System of Interstate and Defense Highways, including the corridor designated as Interstate 40, with federal funding committed to approximately 41,000 miles of controlled-access highways nationwide. This legislation built upon preliminary planning from the Federal-Aid Highway Act of 1944, which had directed the Bureau of Public Roads (BPR) and state highway officials to designate a foundational 40,000-mile network prioritizing efficient, high-mobility routes for commerce and defense. For I-40, the selected alignment emphasized a transcontinental east-west path connecting , to , spanning over 2,550 miles and serving as a primary freight and travel artery across diverse terrain from deserts to mountains. Route planning for I-40 involved collaboration between the BPR, state departments of transportation, and federal officials, who evaluated alignments based on traffic volume projections, topographic feasibility, and economic impact as outlined in the BPR's 1955 "Yellow Book" plan. The chosen corridor largely paralleled established U.S. highways—U.S. Route 66 from California through Arizona, New Mexico, Texas, Oklahoma, and into Arkansas, transitioning to U.S. Routes 70 and 64 eastward—to leverage existing infrastructure while upgrading to divided, limited-access standards with minimum four-lane widths, 70 mph design speeds where possible, and grade-separated interchanges. This selection reflected causal priorities of minimizing construction costs through opportunistic use of proven alignments and maximizing connectivity to population centers and ports, though it required deviations in urban areas for direct routing. Federal designation of the route number occurred in 1957, following approval by the American Association of Officials (AASHO), which adapted a grid-based numbering system for the Interstate network: even numbers for east-west routes, with increments reflecting latitudinal positioning (I-40 positioned as the major east-west spine north of I-30 but south of I-70). The system ensured logical continuity, with I-40 intersecting key north-south interstates like I-15, I-25, I-35, I-55, I-65, and I-95 to form a cohesive grid. Early state-level approvals varied, with raising numbering duplication concerns in November 1957 regarding overlaps with , but the federal framework under the 1956 Act solidified I-40's status, enabling phased funding and right-of-way acquisition thereafter.

Construction Phases by Era

Construction of Interstate 40 accelerated after its inclusion in the via the , with initial contracts awarded in several states by 1957. In , work began in May 1957 on the complex "Figure 8" interchange connecting I-40 and I-65 near Nashville, marking one of the earliest segments funded under the new system. Early efforts in the late 1950s focused on upgrading alignments paralleling in the west and building new corridors in the east, where terrain posed greater challenges. The 1960s represented the primary era of expansion, with hundreds of miles opened across Arizona, New Mexico, Texas, Oklahoma, Arkansas, Tennessee, and North Carolina. In Arkansas, the key I-40/I-30 interchange in North Little Rock was dedicated on November 30, 1962, facilitating connections to Little Rock. Texas construction in the Panhandle advanced rapidly, starting in Amarillo in 1963 and reaching substantial completion by 1965, largely supplanting U.S. 66. Arizona saw active building, including grading near Chambers in 1964 and bridge work over the Rio de Flag near Flagstaff in 1966. By decade's end, core segments from Memphis to Nashville in Tennessee were fully operational, though gaps persisted in mountainous eastern regions. The 1970s emphasized filling gaps and reinforcing western sections, often realigning or widening predecessor routes amid rising traffic from Route 66 decommissioning. Progress slowed in due to funding constraints and environmental reviews, delaying eastern extensions. Final phases spanned the to , addressing remaining rural and coastal segments. 's push to Wilmington, added to the in 1968, faced repeated postponements from federal cuts, achieving full continuity only in after Governor James Martin's administration prioritized completion. This marked the nationwide opening of I-40's 2,556-mile span from to .

Engineering and Geological Challenges

Construction of Interstate 40 presented formidable engineering and geological hurdles due to its 2,556-mile traversal of diverse terrains, including arid deserts, high plains, river valleys, and rugged mountain ranges. In the western segments through , , and , crews navigated expansive desert basins and elevated plateaus, where sparse water resources and extreme temperature fluctuations complicated earthwork and pavement stability, though specific geological instabilities like expansive soils were mitigated through standard stabilization techniques. Further east, crossing the Continental Divide at Campbell Pass in at an elevation of 7,275 feet (2,217 m) required managing steep grades and potential snow accumulation during construction phases in the and . These efforts involved extensive blasting and grading to achieve the interstate's standards of access and high-speed travel. The most acute challenges arose in the Appalachian foothills, particularly the Pigeon River Gorge straddling the Tennessee-North Carolina line, where the route cut through steep, geologically unstable slopes composed of dipping layers prone to fracturing and sliding. Geologists consulting during route planning in the late and early 1960s explicitly warned state engineers that the north bank of the Pigeon River featured strata oriented downward toward the roadway alignment, predisposing it to recurrent ; slides occurred even amid initial earthmoving operations. Despite these forecasts, the path—chosen partly for political reasons to connect regional population centers—was pursued, necessitating innovative but imperfect slope reinforcement methods like retaining walls and drainage systems that have demanded ongoing maintenance. Over the at Memphis, the Bridge's construction from 1969 to 1973 demanded precise cantilever truss assembly for its 900-foot (274 m) main span—the longest open-spandrel in the U.S. at completion—amid constraints of active river barge traffic and alluvial soils requiring deep foundations to counter scour and seismic risks from the nearby New Madrid fault zone. In central segments through the Ozark margins in and rolling terrain in and , flooding potential from rivers like the necessitated elevated alignments and bridge designs, though less severe than mountainous obstructions. These cumulative obstacles delayed full completion until 1987 in , underscoring the trade-offs between expediency and geological realism in mid-20th-century .

Controversies, Eminent Domain, and Opposition

In , construction of I-40 faced significant opposition from residents concerned about its proposed route through Overton Park, a 200-acre public green space established in 1902. Citizens formed the Citizens to Preserve Overton Park group in 1969 to challenge the Federal Highway Administration's approval of the 3.7-mile extension, arguing it violated Section 4(f) of the Department of Transportation Act, which prohibits federally funded highways from traversing public parks unless no feasible alternative exists and all possible planning mitigates harm. The ensuing litigation, Citizens to Preserve Overton Park v. Volpe, reached the U.S. in 1971, which ruled that agency decisions under Section 4(f) required searching to ensure no prudent alternatives were overlooked, though the Court ultimately deferred to the Secretary of Transportation's finding of necessity. Due to sustained protests and legal pressure, the route was adjusted in 1973 to skirt the park's edges rather than bisect it, marking a rare instance where citizen activism altered an Interstate alignment and preserving much of the park's integrity. In , the alignment of I-40 through North Nashville's predominantly African American neighborhoods sparked protests over anticipated community disruption and displacement. The Nashville I-40 Steering Committee, representing affected residents, sued in 1967, contending the route would inflict irreparable harm by severing social and economic ties in the area, with implications of racial targeting given the era's practices that often prioritized white suburbs. The of Appeals rejected the challenge, affirming the state's and traffic justifications, and proceeded from 1968 to 1971, demolishing over 500 structures and displacing thousands via proceedings under law. Critics, including later historical analyses, have attributed long-term socioeconomic decline in North Nashville to the highway's barrier effect, which isolated the community and facilitated , though contemporaneous court records emphasized public need over equity claims. Eminent domain exercises for I-40 right-of-way acquisition involved thousands of parcels across its 2,556-mile span, with states invoking statutory powers to condemn private lands at appraised values often contested by owners. In urban segments like Nashville and , disputes frequently arose over compensation adequacy, as federal funding required uniform appraisals but local valuations varied, leading to trials where landowners argued for higher damages accounting for business losses or sentimental value; for instance, condemned properties along the North Nashville corridor at rates averaging $10,000–$20,000 per lot in dollars, prompting appeals in state courts. Rural oppositions, such as in , centered on fears of city division; a 1957 public hearing saw majority resistance to a central routing, deemed divisive like a "wall," yet the Texas Highway Department selected it for efficiency, acquiring farmlands via with minimal successful challenges. Overall, while enabled timely completion under the 1956 Interstate Highway Act's deadlines, it generated over 1,000 documented condemnation suits along I-40 by 1970, reflecting tensions between federal imperatives for mobility and individual property rights, with success rates for landowners in recovering enhanced awards hovering around 60% in appealed cases.

Primary Auxiliary Routes

I-240 (Oklahoma City, Oklahoma) serves as an urban loop connecting the western and eastern segments of I-40 around , spanning the southern and eastern flanks of the metropolitan area and intersecting I-35 to the south and I-44 to the north. Originally designated in part as I-440 before renumbering to I-240 on December 17, 1974, it supports freight and commuter traffic, including access to . I-440 (Little Rock, Arkansas) functions as a partial beltway linking I-40 northeast of North Little Rock with I-30 and I-530 in Little Rock, forming an eastern bypass for the capital region and aiding truck routing around the urban core. A 4.2-mile extension from I-40 in North Little Rock to U.S. Highway 67/167 (future I-57) in Jacksonville received Interstate designation on August 19, 2025, enhancing connectivity to industrial areas. The route interchanges directly with I-40, promoting efficient east-west movement while avoiding downtown congestion. I-240 (Memphis, Tennessee) provides a southern loop around Memphis, extending 19.27 miles from I-40 in Midtown Memphis eastward to I-40 and Sam Cooper Boulevard, with connections to I-55 and U.S. Highways 51, 64, 70, 72, and 78. Constructed primarily in the 1970s, it alleviates pressure on I-40 through the city by handling local traffic and freight bound for the Memphis International Airport and port facilities. I-140 (Knoxville, Tennessee), known as the Pellissippi Parkway, operates as a spur from the I-40/I-75 interchange west of Knoxville southeastward to the Alcoa and Oak Ridge vicinity, improving access to Oak Ridge National Laboratory and McGhee Tyson Airport. Initial segments opened between 1970 and 1973 to connect the Knoxville metropolitan area with industrial and research sites in Blount and Anderson Counties. I-840 (Nashville, Tennessee) acts as a southern bypass around Nashville, linking I-40 near Dickson in the west to I-40 near Lebanon in the east over 77 miles, intersecting I-65 and providing relief for through traffic on I-40. Developed initially as State Route 840, it received Interstate designation to support regional commerce and suburban growth, though northern extension plans to complete a full loop remain deferred. In , I-140 bypasses Wilmington as the John Jay Burney Jr. Freeway, connecting near Bolton to I-40 southeast of the city over approximately 18 miles, facilitating port and coastal access while diverting traffic from surface routes. I-440 forms the inner Raleigh Beltline, encircling the state capital from I-40/U.S. 1 near Cary to I-40 southeast of Raleigh, aiding circumferential movement in the region. I-540 contributes to the Raleigh outer loop, tying into I-40 near Raleigh-Durham and extending eastward as part of ongoing expansions to complete the beltway.
RouteState(s)TypeKey Connections to I-40
I-140, Spur/BypassDirect at Knoxville (TN); eastern terminus near Wilmington (NC)
I-240, LoopWestern/eastern ends at I-40 (OKC, OK; Memphis, TN)
I-440Arkansas, Partial Loop/BypassNortheastern tie-in (Little Rock, AR); partial encircling (Raleigh, NC)
I-540Outer Loop SegmentInterchange near RDU Airport
I-640Urban LoopConnects western and northern I-40 segments near Knoxville
I-840BypassWestern/eastern ends at I-40 near Dickson and

Business and Spur Routes

Interstate 40 features numerous business loops and spurs that connect the mainline freeway to commercial districts and historic alignments, particularly paralleling former in its western segments. These routes, totaling around 27 across several states, facilitate local access while preserving older roadways, with many overlapping U.S. highways or state routes. In , , , , and , they predominantly trace U.S. 66 paths established before I-40's completion, whereas eastern examples are fewer and often decommissioned. California
A loop serves , spanning 3.4 miles along the National Trails Highway (old U.S. 66 and U.S. 95), linking to State Route 95. Arizona
The state hosts multiple active loops and one , mostly along historic U.S. 66. In Seligman, a 4.25-mile loop overlaps the historic route; Ash Fork has a 1.49-mile loop combining U.S. 66 and old U.S. 89; Flagstaff's 9.51-mile loop, the longest in Arizona, overlaps U.S. 180; Joseph City features a 2.83-mile loop; and Holbrook a 5.09-mile state-maintained segment extending to local maintenance along U.S. 180. Winslow includes both a loop (relinquished in 2007 but reposted in 2021) and a 1.35-mile spur extending westward. Williams maintains a locally signed loop established in 1985, while Kingman's was decommissioned in 2003 and redesignated Historic U.S. 66. New Mexico
Active loops include Moriarty (2.92 miles along old U.S. 66) and Santa Rosa (4.37 miles combining U.S. 66, U.S. 54, and U.S. 84), with Tucumcari's 7.65-mile route overlapping U.S. 54. Former loops in Gallup (now NM 118, 9.5 miles), Grants (replaced by NM 615 and NM 122), and Albuquerque (18 miles along Central Avenue, post-1985) reflect earlier bypasses. Texas
All Texas routes, established between 1990 and 1993, follow historic U.S. 66 alignments and replaced state loops. Active examples are: Glenrio spur (0.779 miles); Adrian loop (2.37 miles); Vega loop (3.40 miles); Amarillo loop (24.4 miles, overlapping U.S. 60); Groom loop (3.53 miles); McLean loop (3.80 miles); and Shamrock loop (2.77 miles). Oklahoma
Oklahoma's eight business routes, six tracing U.S. 66, include active loops in Erick (8.1 miles), Sayre (4.9 miles, overlapping U.S. 283), Elk City (9.5 miles, overlapping SH 6), (5.6 miles), El Reno (8.6 miles, overlapping U.S. 81), Henryetta (3.5 miles, overlapping U.S. 62/75 Business), and Sallisaw (4.0 miles, overlapping U.S. 59/64). Weatherford's 1.47-mile route was decommissioned by 2016; a proposed loop in along the former Crosstown remains unsigned as of 2022. North Carolina
All business loops are former: Winston-Salem/Kernersville (23 miles, decommissioned by 2020, now Salem Parkway overlapping U.S. 421); Greensboro (15.5 miles, eliminated in 2008, overlapped Business I-85); and Raleigh (25.05 miles, replaced by I-440 in 1991 as the former Belt Line). No active routes exist. No business or spur routes are designated along I-40 in or .

Major Intersections and Connections

Key Western Interchanges

The western terminus of Interstate 40 is at a with in , where I-40 branches east across the toward . This junction, completed as part of the Barstow Bypass in 1961, facilitates connections to via I-15 southbound and northbound, handling significant freight traffic from California's ports. In , I-40 intersects at a turbine-style interchange near Flagstaff (I-40 exit 195), providing access south to Phoenix and serving as a critical link for regional travel through the . This junction, which includes bridge replacements completed in recent years to address wear from heavy use and weather exposure, manages high volumes of tourist and commuter traffic, with ongoing improvements to ramps and pavement for safety. Further east in , the "Big I" interchange in Albuquerque connects I-40 with Interstate 25 in a complex configuration, rebuilt between 2005 and 2009 to alleviate congestion in the city's core. Handling over 200,000 vehicles daily across its ramps, this junction integrates east-west transcontinental flow with north-south routes to Santa Fe and El Paso, incorporating operational enhancements like dedicated merge lanes studied as of 2023 to reduce weaving conflicts.

Key Central Interchanges

In Oklahoma City, Oklahoma, Interstate 40 intersects Interstate 35 at the complex Dallas Junction interchange, also involving I-235, facilitating major north-south connectivity along I-35 while handling high-volume east-west traffic through the metropolitan area; this multi-level urban interchange supports over 100,000 vehicles daily and has undergone capacity analyses for lane improvements due to congestion. Further east in the city, I-40 connects with I-240, providing access to southern suburbs and Will Rogers World Airport. Near , I-40 meets in North Little Rock at a critical junction that links the east-west corridor to I-30's route toward Texarkana and ; this interchange, part of the 30 Crossing improvement project completed in phases through 2024, includes reconstructed bridges over the and expanded lanes to accommodate freight and commuter traffic exceeding 150,000 vehicles per day. The configuration allows direct ramps between I-40 eastbound and I-30 eastbound, enhancing flow for regional commerce. In the Memphis area spanning Arkansas and Tennessee, I-40 crosses the Mississippi River via the Hernando de Soto Bridge, where it briefly concurs with I-55 before splitting near West Memphis, forming a vital gateway for Mid-South logistics with the bridge carrying approximately 120,000 vehicles daily prior to a 2021 fracture closure that halted traffic for repairs. This tied-arch structure, spanning 3.3 miles, connects to I-240 in Memphis, distributing traffic to downtown and southern routes. Through , I-40 interchanges with near the city center, where the highways briefly overlap before diverging, serving as a nexus for travel to Louisville northward and Birmingham southward along I-65; this junction handles peak volumes supporting the region's music and healthcare industries, with nearby improvements at Donelson Pike addressing airport access and ramp geometry. The split configuration, updated in the late to eliminate a prior overlap, optimizes directional flow for over 200,000 daily users.

Key Eastern Interchanges

The interchange between Interstate 40 and Interstate 75 near , at mile marker 386, serves as a critical junction connecting the east-west corridor of I-40 with the primary north-south artery of I-75, which links Knoxville to Chattanooga southward and , northward. This cloverleaf-style interchange facilitates a 17-mile overlap of I-40 and I-75 from Farragut westward before they diverge, handling substantial freight and commuter traffic amid noted congestion in Knox County exacerbated by nearby urban access points. Widening projects along this segment, including from Exit 81 to the junction, aim to add capacity to address peak-hour bottlenecks observed in Department of Transportation traffic data. Further east, in , the I-40 interchange with I-26 and I-240 (exits 46-53) forms a complex braided configuration southwest of downtown, integrating access to the and regional routes like US 19/23/70. This junction, part of ongoing NCDOT improvements including lane additions and the proposed I-26 Connector extension, supports connectivity to , via I-26 while navigating mountainous terrain that influences traffic flow and requires frequent maintenance for safety. Daily volumes exceed 100,000 vehicles, contributing to identified bottlenecks addressed through interchange reconstructions. In central , I-40 concurs with I-85 for approximately 60 miles from near Mebane (mile marker 152) to Greensboro (mile marker 212), creating a multi-interchange corridor that merges traffic from the toward the , with key access points at exits like NC 54 and US 15/501. This overlap enhances freight efficiency between Durham and Greensboro but experiences high crash rates in segments, prompting safety enhancements such as express lane feasibility studies. Northeast of Raleigh, the I-40 interchange with I-440, US 1, and US 64 at exits 289-293 represents a high-volume and partial-cloverleaf design accommodating beltway access to the state capital and traffic. Improvements include additions eastward from this point to mitigate congestion, as outlined in Capital Area Metropolitan Planning Organization analyses. I-40 culminates at its eastern terminus in , at an interchange with US 117 and NC 132 (mile marker 420), approximately 0.9 miles north of Kings Grant Road, where signage denotes the route's conclusion after 2,556 miles from . This endpoint, opened in phases through the , provides direct coastal access without a direct tie to I-95, relying instead on US 117 southward.

Economic and Strategic Impact

Freight Transport and Commerce

Interstate 40 serves as a vital east-west freight artery spanning over 2,550 miles from California to North Carolina, designated by the Federal Highway Administration as part of the National Primary Freight Network to prioritize goods movement critical to national commerce. It connects Pacific Coast ports, such as those in California, to manufacturing hubs, agricultural regions, and eastern distribution centers, handling diverse commodities including automobiles, chemicals, consumer goods, and agricultural products. In states along its route, I-40 supports logistics-intensive economies by enabling efficient truck-based transport, which accounts for approximately 40% of national truck vehicle-miles traveled on Interstate highways. Truck traffic volumes underscore I-40's freight dominance, with segments in showing daily truck counts of 5,800 to 8,100 vehicles, comprising 31% to 45% of total traffic and peaking at over 8,000 trucks at ports of entry like Topock. In , the corridor's heaviest traveled Interstate segment, trucks represent 4% to 38% of overall traffic, reflecting its role in moving 71% to 77% of inbound and outbound freight by truck. Annual freight throughput in reaches 770 million tons, with 95% involving interstate flows in key sectors like advanced manufacturing and . The economic contributions of I-40's freight operations are substantial, sustaining over 10,600 trucking firms in alone that employ 4% of the state's workforce and supply 85% of its communities. Projections forecast a doubling of statewide freight by 2040, with the I-40 corridor experiencing over 70% growth in by 2045, driven by and increases of 15% and 30%, respectively, in adjacent counties. This lowers shipping costs, enhances —reaching 65% of U.S. centers in one day from —and bolsters regional trade hubs like Memphis and , though high truck percentages contribute to bottlenecks that delay commerce.

Regional Development and Tourism

Interstate 40 has enhanced by improving accessibility to remote areas and urban hubs, thereby supporting and in states from to . In , the corridor connects Flagstaff to key economic activities, including logistics and manufacturing tied to its east-west linkage. The highway significantly boosts by providing primary access to major attractions. In , I-40 serves as the main travel corridor for 60.1% of visitors, facilitating entry from the east and supporting over 20 national parks, monuments, and recreation areas along the route. This connectivity draws millions annually to sites like and historic Route 66 landmarks parallel to the interstate. Further east, I-40 underpins tourism-dependent economies in and , where closures from events like rockslides result in substantial losses in visitor spending and business sales. In , the I-40 extension to Wilmington correlated with a 146% rise in tourism's economic impact from 1991 to 2008, enabling growth in and related sectors. Cities such as Memphis and Nashville leverage the route for music , while access to from Knoxville and Asheville sustains regional visitor economies.

Military and National Security Role

Interstate 40 contributes to national defense as an integral element of the National System of Interstate and Defense Highways, established under the to facilitate rapid deployment of troops, vehicles, and across the continent during emergencies or conflicts. Design features, including wide lanes, gentle curves, and bridges capable of supporting heavy loads like tanks and , reflect military requirements incorporated from the outset to enable efficient without extensive reconfiguration. The highway's western terminus at , adjoins the Marine Corps Logistics Base Barstow, a critical depot for maintenance, repair, and storage of Marine Corps ground combat systems, including tanks and wheeled vehicles. Positioned at the intersection of I-40, I-15, and historic , the base utilizes the route for inbound shipments of parts via rail and truck, supporting overhaul of over 1,000 major end items annually and ensuring readiness for expeditionary forces. Central segments near provide vital access to , the U.S. Air Force's largest maintenance and sustainment center, where a 10-mile portion of I-40 was designated the "Freedom Freeway" in 2007 to commemorate the base's contributions to aircraft depot-level repairs and global logistics. This connectivity aids transport of oversized cargo, such as jet engines and avionics, sustaining operations for platforms like the B-52 and KC-135. Further east in , I-40 links to , a primary C-130 Hercules hub for tactical airlift, enhancing intra-theater mobility. Eastern extensions form part of the Strategic Highway Network (STRAHNET), prioritizing defense mobility, and integrate into corridors connecting to in , the Defense Department's principal East Coast ammunition port handling over 1.2 million tons of munitions yearly. These links support supply lines to installations like Fort Liberty (formerly Fort Bragg), bolstering overall through resilient east-west throughput.

Safety, Maintenance, and Incidents

Accident Statistics and Safety Improvements

Interstate 40, as a primary east-west freight corridor carrying over 20% of the nation's traffic in sections, exhibits crash rates influenced by high volumes, variable , and interchanges, with data indicating elevated severe crash frequencies in rural and mountainous segments compared to state averages. In Arizona's I-40 East corridor (mileposts 195–359), analysis of 2015–2019 data revealed 56 fatal crashes, 76 suspected serious injury crashes, and 132 combined severe incidents, with 39% involving collisions, 40% vehicle overturns, and 38% involvement in high-frequency areas like milepost 195–196 near Flagstaff. segments similarly show fatal and serious injury rates exceeding statewide norms, driven by geometric deficiencies such as tight curves and short ramps, alongside rear-end and fixed-object collisions comprising major types. In , I-40 recorded 10 fatal accidents in 2021, concentrated at urban interchanges amid statewide trends of 762 fatalities that year. High-risk locations cluster around terrain transitions, such as 's Canyon Diablo (mileposts 212–234, with 11 fatal and 16 serious injury crashes from 2015–2020) and Holbrook (mileposts 288–290, weather- and lighting-related), where 50% of severe crashes occur in unlit conditions. Contributing factors include lane departures (91 corridor-wide from 2010–2014 in ), drug/alcohol involvement (23%), and inadequate shoulders, exacerbating rollover risks for heavy vehicles. State-reported data underscores that truck-heavy traffic amplifies severity, as evidenced by 27 truck-involved crashes in 's analyzed segments. Safety enhancements, often funded via the Federal Highway Administration's Highway Safety Improvement Program, target these vulnerabilities through infrastructure and operational upgrades. In , prioritized countermeasures include $8.06 million in installations at mileposts 196–202 to mitigate nighttime risks, rehabilitation, skid resistance improvements, and dynamic message signs for variable speed limits. New plans widening to 12 feet, ramp extensions meeting design standards, curve realignments, and emergency crossovers to enhance incident response and reduce secondary crashes. North completed widening of I-40 from four to six lanes east of Statesville by September 2025, alongside ramp revisions at the I-40/I-77 interchange to improve merge safety. Tennessee's projects, such as acceleration/deceleration lane additions at the McCrory Lane interchange, address ramp-related collisions, while 's ongoing pavement rehabilitation on 57 miles in 2025 incorporates rumble strips and high- delineators. These interventions, evaluated via crash reduction factors, aim to lower severe incident rates by addressing causal elements like and .

Notable Crashes and Structural Failures

On May 26, 2002, the I-40 bridge over the Arkansas River near Webbers Falls, Oklahoma, partially collapsed after the towboat Robert Y. Love allided with a pier while pushing two empty asphalt barges. The pilot's fatigue-induced microsleep caused the tow to veer off course, striking the pier and dropping a 580-foot section of the bridge into the river, killing 14 people—including 10 from a school bus—and injuring five others. The National Transportation Safety Board determined the primary cause as the pilot's drowsiness, compounded by inadequate rest and lack of bridge protection systems. On May 11, 2021, the spanning the on I-40 between , and , was abruptly closed after Arkansas inspectors identified an 18-inch crack in a fracture-critical tie via drone inspection. The defect, resulting from over decades of service since 1973, threatened imminent under load, averting through rapid traffic halt and subsequent emergency reinforcements involving steel plating and cable stays. The bridge reopened in phases by August 2021 after $20 million in repairs, highlighting vulnerabilities in older tied-arch designs to cyclic loading. In the Pigeon River Gorge, heavy rains and flooding from Hurricane Helene on September 27, 2024, triggered mudslides that eroded and collapsed multiple sections of I-40 near the Tennessee-North Carolina state line, including over 10 failure sites in a 4-mile stretch. The geotechnical instability washed away pavement and substructure, stranding vehicles but causing no reported fatalities from the collapses themselves, though the event exacerbated regional disruptions from the storm. Reconstruction efforts, involving stabilization and new abutments, delayed full reopening until early 2025, underscoring the highway's exposure to Appalachian flash flooding.

Recent Repairs and Natural Disaster Response

In May 2021, routine inspections revealed a in the steel tie-girder box section of the , which spans the carrying I-40 between , and , prompting immediate closure of the 3.3-mile structure to all traffic. Emergency response involved collaborative efforts by the Arkansas and Tennessee Departments of Transportation, with Phase 1 repairs—installing temporary stabilization plating—completed in 14 days to restore partial capacity. Eastbound lanes reopened on July 31, 2021, followed by westbound lanes on August 6, 2021, after further inspections and concrete patching at multiple sites. These repairs addressed structural vulnerabilities without evidence of external disaster causation, focusing on fatigue-related cracking in the aging 1970s-era bridge. Hurricane Helene struck on September 27, 2024, unleashing catastrophic flooding from the Pigeon River that eroded over half a mile of I-40's eastbound lanes near the border, collapsing embankments and stranding dozens of vehicles in undermined sections. (NCDOT) and Tennessee Department of Transportation (TDOT) mounted rapid response operations, including drone assessments and evacuations, while federal aid facilitated debris clearance and temporary stabilization using soil nail walls covering 128,000 square feet to support one lane of traffic. The interstate segment reopened to restricted one-lane-each-direction traffic on March 1, 2025, marking the first connectivity since the storm. Full reconstruction, incorporating massive retaining walls and advanced embankment reinforcement, is projected for completion by September 2028, with NCDOT reporting repairs at over 6,500 statewide sites by September 2025 amid $1.5 billion in federal emergency relief funding. These efforts underscore I-40's vulnerability to Appalachian flash flooding, where steep terrain amplifies runoff volumes exceeding design capacities, though no comparable wildfire or seismic events have necessitated similar-scale interventions along the corridor since 2020.

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