The Memphis & Arkansas Bridge, also known as the Memphis–Arkansas Bridge or inaccurately as the Memphis–Arkansas Memorial Bridge, is a cantilevered through truss bridge carrying Interstate 55 across the Mississippi River between West Memphis, Arkansas and Memphis, Tennessee. Memphians refer to this bridge as the "Old Bridge" to distinguish it from the "New Bridge", or Hernando de Soto Bridge, upstream.

The Memphis & Arkansas Bridge also carries U.S. Route 61 (US 61), US 64, US 70, US 78, and US 79 from Memphis to West Memphis; it also carried US 63 prior to its truncation (and later rerouting) in Arkansas. The western terminus of Tennessee State Route 1 (SR 1) sits on the Tennessee–Arkansas boundary halfway across the bridge.

Opened in 1949, the bridge is currently the oldest bridge on the Interstate Highway System in Tennessee and Arkansas. It is currently planned to be replaced with a larger and wider bridge, starting in 2026.

The bridge consists of five Warren through trusses, each with a length of 790 feet (240 m). Combined with the approach segments, the bridge's total length is 5,222 feet (1,592 m). Completed in 1949, it is the only bridge spanning the Mississippi River designed to carry exclusively vehicular traffic that was built before 1950. It was designed by Modjeski and Masters, successors to the firm that designed the Harahan Bridge, built in 1916 to carry vehicular and rail traffic. The bridge was listed on the National Register of Historic Places in 2001.

Built before the introduction of the Interstate Highway System, the span was not built to Interstate Highway standards; it originally lacked the concrete barrier between the different directions of traffic which, was added later. It was also built with a sidewalk on either side of the roadway, positioned just outside the steel truss girders. The sidewalks, now also separated from the traffic lanes by concrete barriers, are accessible from Memphis city sidewalks on the Tennessee side, but give way to grassy slopes on the shoulders of I-55 on the Arkansas side.

The sidewalk and bridge is listed as part of the Mississippi River Trail. However, travel is not recommended across the sidewalk and is prohibited on the vehicle traffic lanes of the bridge, as the structure is an Interstate Highway crossing. In 2016, a pedestrian/bicycle path on the neighboring Harahan Bridge made crossing the river safer and eliminated the need to use the I-55 bridge.

Despite common references to this bridge as a "Memorial Bridge", most likely resulting from its opening shortly after World War II, there is no evidence that this bridge was ever intended to be a memorial to anything. There is no mention of any memorial intent on the bridge's nameplates, including a dedicatory poem on one nameplate (officially attributed to Walter Chandler) that appears to focus on the traffic expected to cross the bridge rather than any memorial. (This is in contrast to the Harahan Bridge, which was named for a railroad executive who died in an accident during the bridge's construction.) Crump himself, for whom the boulevard originally leading to the bridge was named, lived until 1954; Chandler lived until 1967.

The Memphis & Arkansas Bridge was inspired by the ever increasing flow of traffic on the single-lane cantilevered "wagonways" of the Harahan Bridge from its opening in 1916 all the way to this bridge's opening in 1949. This increased traffic led to the incorporation of West Memphis, Arkansas, in 1927 where the Arkansas roadways leading to the Harahan Bridge came together, as well as the 1930 replacement by the Arkansas State Highway Commission (ASHC), the modern-day version of which oversees the Arkansas Department of Transportation, of the original wooden viaduct leading from West Memphis to the Harahan Bridge. Most of the 1930 viaduct was reused for the Memphis & Arkansas Bridge until the present I-55 viaduct replaced it in the 1980's; a small portion of that viaduct now serves as the Arkansas entrance to the Harahan Bridge's Big River Crossing (built on one of its former "wagonways").