Time in Texas

Time in Texas primarily follows the Central Time Zone (UTC-6 standard, UTC-5 daylight saving), encompassing the vast majority of the state's land area and population, while a narrow western strip—including El Paso, Hudspeth, and northwestern Culberson counties—observes the Mountain Time Zone (UTC-7 standard, UTC-6 daylight saving).^[1][2] This division stems from geographical alignment with neighboring states and historical adjustments under the Standard Time Act, with West Texas retaining Mountain Time to synchronize with New Mexico and Arizona regions despite the state's predominant Central orientation.^[3][1] Texas adheres to federal daylight saving time (DST) protocols, advancing clocks by one hour from the second Sunday in March to the first Sunday in November, a practice that has persisted since the Uniform Time Act of 1966 despite periodic local debates over its efficacy.^[4] In May 2025, the Texas Legislature passed House Bill 14 to adopt permanent DST year-round, eliminating biannual changes, but implementation requires U.S. Congressional approval, leaving the state subject to seasonal shifts as of October 2025.^[5][6] This arrangement affects commerce, energy use, and daily routines, with the time zone split occasionally complicating coordination in border areas like El Paso, where economic ties to Mexico and the Pacific Time-adjacent Southwest amplify cross-border temporal discrepancies.^[1][7] Proposals to unify Texas under a single time zone have surfaced historically but face resistance due to entrenched regional differences and federal constraints on state-level alterations.^[3]

Current Time Zones

Central Time Zone Coverage

The Central Time Zone encompasses the vast majority of Texas, including all major population centers and economic hubs such as the Dallas-Fort Worth metroplex, Houston, San Antonio, Austin, and Amarillo.^[1] This coverage extends from the eastern borders with Louisiana and Arkansas westward across the state's central and eastern regions, up to the irregular boundary in West Texas near the New Mexico state line.^[2] The zone operates on UTC-6 hours during Central Standard Time and advances to UTC-5 during daylight saving time observance.^[1] Texas's Central Time observance includes 251 of its 254 counties, excluding El Paso County and Hudspeth County, which fully adhere to Mountain Time, and the northwestern portion of Culberson County, particularly around Guadalupe Mountains National Park.^[1] Most of Culberson County, including the city of Van Horn, follows Central Time to maintain alignment with adjacent Central Time areas in Texas.^[1] This division reflects historical adjustments to standardize time across rail and commercial networks, prioritizing synchronization with the state's predominant economic activities over strict longitudinal meridians.^[2] The Central Time boundary in Texas generally follows county lines in the west but deviates in Culberson County to accommodate local usage patterns, ensuring that key transportation corridors like Interstate 10 and U.S. Route 62/180 remain consistent with Central Time east of the full Mountain Time counties.^[1] Cities like Odessa, Lubbock, and Abilene, which serve agricultural and oil-producing regions, also observe Central Time, facilitating coordination with markets in the state's core.^[8] This broad coverage supports Texas's role as a central node in national commerce, where time alignment with Midwestern and Southern states minimizes disruptions in supply chains and broadcasting.^[2]

Mountain Time Zone Areas

The Mountain Time Zone in Texas covers a small portion of the state's far western region, primarily El Paso County and Hudspeth County, which officially observe Mountain Standard Time (MST, UTC-7) during standard time and Mountain Daylight Time (MDT, UTC-6) during daylight saving time periods.^[1] These counties encompass approximately 10,000 square miles, with El Paso County alone accounting for the majority of the area's land and population.^[1] El Paso, the principal city in this zone, had a population of 678,815 as of the 2020 United States Census, making it the westernmost major urban center aligned with Mountain Time rather than the predominant Central Time observed elsewhere in Texas. Hudspeth County, sparsely populated with about 3,274 residents per the 2020 Census, includes communities such as Sierra Blanca, the county seat, and relies on Mountain Time for synchronization with neighboring New Mexico and alignment with interstate commerce along Interstate 10. This county's inclusion in Mountain Time stems from historical petitions dating to the 1960s, formalized under amendments to the Uniform Time Act of 1966, which permitted local exceptions to federal time zone boundaries to reflect economic ties to adjacent states.^[9] Additionally, the northwestern corner of Culberson County, near Guadalupe Mountains National Park, unofficially adheres to Mountain Time due to its proximity to New Mexico and practical coordination needs for park operations and cross-border activities, despite the county's official designation in Central Time.^[10] This unofficial observance affects a limited area, including park facilities, but does not extend to the county's main population center of Van Horn, which follows Central Time.^[11] The time zone boundary in western Texas generally approximates the 105th meridian west but deviates to follow county lines for administrative simplicity, ensuring that these Mountain Time areas facilitate trade and communication with Mountain Time regions in New Mexico and Arizona.^[8]

Daylight Saving Time

Observance Schedule

Daylight saving time (DST) in Texas commences at 2:00 a.m. local standard time on the second Sunday in March, when clocks are advanced one hour to 3:00 a.m. local DST.^[12][4] It concludes at 2:00 a.m. local DST on the first Sunday in November, when clocks are set back one hour to 1:00 a.m. local standard time.^[12][4] This schedule, established by the federal Energy Policy Act of 2005, applies uniformly across Texas's Central and Mountain Time Zone areas, with no county-level exemptions currently in effect.^[12][13] For 2025, DST began on March 9 and is scheduled to end on November 2, aligning with the national observance mandated under the Uniform Time Act as amended.^[4][14] Texas state law requires adherence to these federal dates unless Congress authorizes permanent DST, a change proposed in recent legislation like House Bill 1393 but not yet implemented as of October 2025.^[5][7] During DST, Central Time shifts from UTC-6 to UTC-5, while Mountain Time shifts from UTC-7 to UTC-6, extending evening daylight by one hour in summer months.^[4][13]

Legislative History and Proposals

Texas has observed daylight saving time (DST) since the federal Uniform Time Act of 1966 mandated its observance nationwide, with states permitted to opt out via legislative action.^[15] Prior to 1966, Texas experimented with DST during World War I and II under federal wartime measures but largely abandoned it postwar until standardization.^[15] The state legislature has not enacted statewide opt-outs since, maintaining seasonal clock changes aligned with federal schedules—advancing clocks on the second Sunday in March and reverting on the first Sunday in November.^[16] In recent sessions, Texas lawmakers have introduced competing bills to eliminate biannual changes, either by adopting permanent DST (requiring congressional approval under the Uniform Time Act) or permanent standard time (feasible unilaterally). The 88th Legislature (2023) saw House Bill 1422 pass the House 138-5, directing the state to observe year-round DST contingent on federal authorization via the Sunshine Protection Act, though it stalled in the Senate.^{[17] [18]} Earlier, House Bill 165 (2023) sought similar permanent DST but died in committee.^[19] The 89th Legislature (2025) advanced House Bill 1393, which passed the House and Senate before Governor Greg Abbott signed it into law on June 23, 2025, authorizing permanent DST for Texas's Central and Mountain zones if Congress amends federal law to permit it.^{[5] [20]} The bill, dubbed "Texas Time," takes effect September 1, 2025, but remains inactive without federal changes, preserving current observance through at least November 2, 2025.^{[21] [22]} Counterproposals favor permanent standard time to opt out of DST entirely. Senate Bill 64 (2025), introduced by Senator Paul Bettencourt, proposes year-round standard time and a November 4, 2025, referendum for voters to express preference between standard time or DST year-round, potentially enabling opt-out as early as January 1, 2026, if approved.^{[23] [24]} Senate Bill 692 (2025) similarly amends government code to address DST observance.^[25] Advocates cite health and safety data, arguing clock shifts disrupt circadian rhythms without proven energy savings, though these bills face opposition from commerce interests favoring extended evening light.^[26] Texas Policy Research, a conservative think tank, supports standard time exemption, noting over 750 similar state bills nationwide since 2018.^{[16] [26]} No such opt-out has passed, leaving Texas bound by federal DST mandates.^[27]

Historical Development

Pre-Standard Time Era

Prior to the establishment of standard time zones in 1883, timekeeping in Texas relied on local solar time, where communities set clocks and public signals based on the sun reaching its zenith over their specific meridian. This resulted in variations across the state's east-west span of roughly 12 degrees of longitude—from about 94° W near the Louisiana border to 106° W at El Paso—equating to up to 48 minutes of difference in local noon between extremities like Beaumont and El Paso. Larger settlements used sundials, church bells, or tower clocks for synchronization, while rural areas often depended on natural solar cues such as shadow lengths or rooster crows for approximate divisions of the day.^[3][28] Mechanical timepieces entered Texas with Anglo-American and European immigrants in the early to mid-19th century, initially through the port of Galveston, which by 1848 served as a hub for trade and settlement. German and Czech migrants arriving en masse from 1840 to 1870 imported clocks, boosting local horology in German-settled hill country towns like New Braunfels and Fredericksburg. Notable early installations included a Seth Thomas clock at the Menger Hotel in San Antonio upon its 1859 opening and a tall case clock acquired for the governor's mansion during Elisha M. Pease's administrations (1853–1857 and 1867–1869). Clock peddlers traversed rural areas in the mid-1850s, employing persuasive tactics to sell imported East Coast models, though many households retained sun-based routines due to the devices' high cost and maintenance demands.^[29] Railroad construction, commencing with a 20-mile line from Galveston to Virginia Point in 1853 and expanding to over 8,500 miles by 1890, amplified the challenges of local time disparities, as train schedules necessitated some route-specific coordination. Operators adopted provisional "railroad time" for timetables, diverging from pure solar local time to minimize delays between stations separated by mere minutes of longitude. On plantations, clocks enforced regimented work hours under the task system, reflecting broader antebellum efforts to impose temporal discipline amid slavery, yet overall practices remained fragmented until national standardization resolved the inconsistencies for commerce and travel.^[29][30]

Federal Standardization and Texas Adoption

The push for standardized time in the United States originated with the railroad industry, which on November 18, 1883, voluntarily implemented four continental time zones—Eastern, Central, Mountain, and Pacific—to synchronize schedules and reduce accidents from disparate local solar times.^[30] In Texas, major railroads such as the Texas and Pacific Railway adopted this system, designating the entire state as part of the Central Time Zone, despite its longitudinal span suggesting potential division.^[3] Federal legislation formalized these zones through the Standard Time Act of 1918, signed by President Woodrow Wilson on March 19, 1918, which legally defined the boundaries under the oversight of the Interstate Commerce Commission (ICC) and introduced daylight saving time as a wartime energy measure effective March 31, 1918.^[12] The Act applied nationwide, including Texas, where implementation began with standard time observance from October 1918, though the zones took full legal effect January 1, 1919.^[31] Texas communities, reliant on rail transport, transitioned accordingly, but the ICC's delineation along the 100th meridian placed most of the state in Central Time while assigning far West Texas—including El Paso and initially the Panhandle—to Mountain Time, diverging from the prior uniform railroad practice.^[3] This federal split prompted immediate local resistance in Texas, particularly in the Panhandle, where business leaders argued economic ties to Central Time states like Oklahoma warranted reversion; the Panhandle-Plains Chamber of Commerce petitioned the ICC by November 1919 for adjustment, highlighting disruptions to commerce and agriculture.^[3] No Texas state legislation was required for initial adoption, as interstate rail regulation fell under federal purview, but subsequent ICC approvals in the early 1920s realigned the Panhandle to Central Time while retaining Mountain Time for El Paso and surrounding counties to align with New Mexico and Arizona practices.^[3] These adjustments underscored Texas's accommodation of federal standards amid regional geography and economic pressures, without formal opt-outs or exemptions at the state level.^[12]

Boundary Shifts and Adjustments

The initial establishment of standard time zones in the United States under the Standard Time Act of 1918 placed the Texas Panhandle and Plains regions in the Mountain Time Zone alongside parts of New Mexico and Oklahoma.^[9] This alignment reflected geographic longitude considerations, as the Panhandle's position west of the 100th meridian suggested compatibility with Mountain Time. However, local economic ties, particularly rail and commerce connections to Central Time areas like Oklahoma and eastern Texas, prompted rapid reevaluation.^[9] In March 1921, Congress amended the Standard Time Act, transferring the Panhandle and Plains sections of Texas—along with corresponding areas in Oklahoma—to the Central Time Zone.^[32] This shift, codified in 15 U.S.C. § 265, addressed discrepancies in transportation schedules and business operations, ensuring synchronization with major Central Time hubs such as Amarillo's rail networks.^[9] The change took effect promptly, resolving a brief two-year period of Mountain Time observance from 1919 to 1921 and establishing the Panhandle's enduring Central Time alignment.^[33] Western Texas, including El Paso, initially followed Central Time under the 1918 framework but maintained de facto Mountain Time usage due to proximity to Arizona and New Mexico, as well as cross-border commerce with Ciudad Juárez.^[34] The 1921 congressional adjustment explicitly placed all of Texas in Central Time, yet El Paso residents and businesses largely disregarded the mandate, continuing Mountain Time practices to avoid desynchronization with neighboring regions.^[35] This noncompliance persisted for decades, fueled by petitions from local chambers of commerce citing economic and solar time advantages.^[35] Formal recognition came on April 10, 1970, when an amendment to the Uniform Time Act (15 U.S.C. § 260 et seq.) exempted El Paso and Hudspeth counties from Central Time, permitting their placement in the Mountain Time Zone.^[34] The legislation stated: "Notwithstanding the first section of the Act of March 4, 1921 (15 U.S.C. 265), the Standard Time of the zone designated as Mountain Standard Time under such section shall be observed in El Paso and Hudspeth Counties, Texas."^[36] This adjustment aligned legal boundaries with longstanding local observance, preventing further federal-local friction. Subsequent minor refinements included portions of Culberson County in Mountain Time by the 1980s, though no major statewide boundary alterations have occurred since.^[37] These shifts underscore the interplay of geography, economics, and federal oversight in defining Texas's time zones, with boundaries remaining largely stable into the present.^[12]

Technical Standards

IANA Time Zone Identifiers

The IANA Time Zone Database, maintained by the Internet Assigned Numbers Authority, provides standardized identifiers for representing local time offsets, rules for daylight saving time (DST), and historical changes across locations. These identifiers follow a continent/city convention and are used in computing systems to accurately compute timestamps. Texas, spanning the Central and Mountain Time Zones, utilizes two primary IANA identifiers corresponding to its geographic and legal time divisions.^[38] For the vast majority of Texas—encompassing about 98% of the state's land area and population, including major metropolitan areas such as Houston, Dallas, Austin, and San Antonio—the identifier America/Chicago applies. This represents the Central Time Zone, with standard offset UTC-06:00 (Central Standard Time, CST) and DST offset UTC-05:00 (Central Daylight Time, CDT), adhering to U.S. federal DST rules since 1966, including the Energy Policy Act of 2005 extension from early April to early November. Cities like Dallas explicitly use America/Chicago for precise time handling.^[39][40][41] The western extremity of Texas, specifically El Paso County, Hudspeth County, and portions of adjacent areas like northwestern Culberson County, falls under the Mountain Time Zone and uses the identifier America/Denver. This identifier denotes UTC-07:00 standard (Mountain Standard Time, MST) and UTC-06:00 DST (Mountain Daylight Time, MDT), synchronized with neighboring regions in New Mexico and Arizona (though Arizona largely skips DST). El Paso, the principal city in this region, relies on America/Denver for system clocks and legal time references, ensuring alignment with trans-border commerce and transportation.^[39][42][43] No additional IANA identifiers are designated exclusively for Texas; the state inherits the broader North American zone rules via these representative locations, which encapsulate all relevant historical adjustments, such as pre-2007 DST start dates on the first Sunday in April. Software implementations query these IDs to apply Texas-specific observance without custom overrides, promoting interoperability in global time computations.^[44]

Synchronization and Legal Definitions

The standard time in Texas is defined by Texas Government Code § 312.016 as the time of the 90th meridian of longitude west from Greenwich, known as central standard time, applicable statewide unless otherwise specified in statutes, orders, or rules.^[45] Certain western areas, including those that observed mountain standard time prior to June 12, 1947, continue to use mountain standard time, defined by the 105th meridian west from Greenwich.^[45] These definitions align with federal standards under the Standard Time Act of 1918, as amended, which establish uniform time zones across the United States.^[12] Time zone boundaries within Texas are delineated by federal regulation in 49 CFR Part 71, which specifies geographic limits rather than strictly following county or state lines.^[46] The majority of Texas, encompassing over 250 counties, falls within the Central Time Zone, while El Paso County, Hudspeth County, and the northwestern portion of Culberson County observe Mountain Time.^[32] Adjustments to these boundaries, such as the 1961 transfer of the Texas Panhandle and Plains to the Central Time Zone, require approval from the U.S. Department of Transportation to ensure consistency with commerce and transportation needs.^[32] Synchronization of clocks to these legal standards occurs through dissemination of the official U.S. time by the National Institute of Standards and Technology (NIST), which maintains atomic clocks referenced to Coordinated Universal Time (UTC). In Texas, as elsewhere in the nation, practical synchronization relies on NIST's radio broadcasts from station WWVB in Colorado, which transmit time signals receivable across the state for radio-controlled clocks, or satellite-based Global Positioning System (GPS) signals providing UTC traceable to NIST. Network Time Protocol (NTP) servers hosted by NIST enable internet-based synchronization for computers and networks, ensuring sub-second accuracy relative to UTC(NIST), from which local standard time is derived by subtracting the appropriate offset (six hours for Central, seven for Mountain).^[47] Legal adherence requires public clocks, official records, and commercial activities to conform to the designated standard time, with daylight saving time observance—currently seasonal under the Uniform Time Act of 1966—advancing clocks by one hour from the second Sunday in March to the first Sunday in November.^[12] House Bill 1393, signed into law on June 23, 2025, permits Texas to adopt permanent daylight saving time statewide (termed "Texas Time") upon congressional authorization, but as federal approval remains pending, seasonal changes persist, with the next "fall back" occurring November 2, 2025.^[5][48] This conditional provision applies uniformly to both time zones without altering base standard time definitions.^[45]

Debates and Empirical Evidence

Arguments Surrounding DST

Proponents of Daylight Saving Time (DST) in Texas argue that it extends evening daylight during warmer months, facilitating outdoor activities, retail commerce, and recreation, which could boost economic activity. For instance, supporters claim DST aligns better with human behavior by providing more light after typical work hours, potentially reducing evening traffic accidents and crime rates due to increased visibility. In Texas, where the legislature passed House Bill 1393 in May 2025 to adopt permanent DST—pending federal approval—advocates like state lawmakers emphasized these benefits, citing alignment with national trends and avoidance of biannual clock changes that disrupt schedules.^[5][49] However, these claims rely on observational correlations rather than causal evidence, and Texas-specific data on crime or accident reductions remains anecdotal without rigorous statewide analysis. Opponents, including some Texas policymakers and health experts, contend that DST's spring-forward shift acutely disrupts circadian rhythms, leading to measurable health risks such as increased incidences of myocardial infarction, stroke, and overall mortality in the weeks following the transition. Peer-reviewed studies, including those from the American Academy of Sleep Medicine, link the loss of sleep to heightened cardiovascular morbidity, with the spring DST onset associated with a 6-24% rise in heart attacks in affected populations.^[50][51][52] In Texas, groups like the Texas Public Policy Foundation have advocated ending DST entirely in favor of permanent standard time, arguing the ritual imposes unnecessary biological stress without offsetting gains, particularly for rural areas where farming schedules conflict with darker mornings.^[26] The purported energy savings from DST have been a cornerstone argument but lack empirical support; a 2018 meta-analysis of 44 studies across countries found only a negligible 0.34% reduction in electricity use, often offset by increased air conditioning demand in hot climates like Texas summers.^[53] U.S. Department of Energy evaluations of extended DST periods similarly reported minimal national savings of about 0.5%, with regional variations showing no consistent benefit in southern states.^[54] Critics in Texas highlight that opting for permanent standard time would better synchronize clocks with solar noon, minimizing misalignment that exacerbates sleep debt and productivity losses, as evidenced by post-transition spikes in workplace errors and hospital admissions.^[55][56] Texas's debate reflects broader national tensions, with the 2025 bill for permanent DST signed by Governor Greg Abbott but stalled by federal law under the Uniform Time Act, which prohibits states from unilateral permanent adoption without congressional consent. While some counties in far West Texas already forgo DST by adhering to year-round Mountain Standard Time, statewide implementation faces opposition from health organizations recommending permanent standard time for optimal safety and well-being, prioritizing natural light in mornings over artificial evening extensions.^[20][57] Empirical data thus weighs against DST's net benefits, underscoring disruptions to human physiology over unproven economic or safety advantages.

Data on Energy, Health, and Safety Effects

Empirical analyses of daylight saving time (DST) in the United States, including regions with climates similar to Texas, indicate negligible net energy savings, often offset by increased air conditioning demand during extended evening daylight hours. A U.S. Department of Energy study on extended DST found electricity consumption decreased by only 0.03% nationally in 2007, with savings primarily from reduced lighting but counterbalanced by higher cooling loads in warmer states.^[58] An Indiana statewide experiment revealed no overall reduction in electricity use, with some counties experiencing slight increases due to behavioral shifts in energy patterns.^[59] Reviews of multiple U.S. studies conclude the evidence for DST-induced savings is inconclusive, typically under 0.5% of total usage, and potentially negative in air-conditioned environments like Texas summers.^[60] Health impacts from biannual clock transitions stem from circadian rhythm disruptions, with the spring shift to DST showing acute risks. Meta-analyses link the March time change to a 6-24% increase in myocardial infarction incidence in the following week, attributed to sleep deprivation and misalignment with solar time.^[50] Stroke hospitalizations rise similarly post-transition, alongside elevated rates of atrial fibrillation and other cardiovascular events.^[55] The American Academy of Sleep Medicine advocates permanent standard time, citing chronic misalignment under DST as exacerbating sleep disorders, mood disturbances, and metabolic issues like obesity.^[57] These effects are consistent across U.S. populations, including Texas, where extended DST periods amplify misalignment during high-heat seasons. Safety data highlight elevated risks from DST transitions, particularly traffic fatalities and injuries due to fatigue. Fatal car crashes increase by approximately 6% in the week following the spring DST onset, driven by drowsy driving from lost sleep.^[61] In Texas specifically, analyses of state crash data show a comparable 6% spike in deadly accidents post-change, with peak risks in morning hours before circadian adjustment.^[62] The fall shift back adds evening hazards from sudden darkness during commutes, correlating with higher pedestrian and vehicle collisions, though less pronounced than spring effects. Workplace injuries and overall accident rates also rise transiently, underscoring causal links to sleep disruption rather than lighting benefits.^[63]