Interstate 40 in Tennessee

Interstate 40 (I-40) is part of the Interstate Highway System that runs 2,556.61 miles (4,114.46 km) from Barstow, California, to Wilmington, North Carolina. The highway crosses the state of Tennessee from west to east, from the Mississippi River at the Arkansas state line to the Blue Ridge Mountains at the North Carolina state line. At 455.28 miles (732.70 km), the Tennessee segment of I-40 is the longest of the eight states through which it passes and the state's longest Interstate Highway.

I-40 passes through Tennessee's three largest cities—Memphis, Nashville, and Knoxville—and serves the Great Smoky Mountains National Park, the most-visited national park in the United States. It crosses all of Tennessee's physiographic regions and Grand Divisions—the Mississippi embayment and Gulf Coastal Plain in West Tennessee, the Highland Rim and Nashville Basin in Middle Tennessee, and the Cumberland Plateau, Cumberland Mountains, Ridge-and-Valley Appalachians, and Blue Ridge Mountains in East Tennessee. Landscapes on the route vary from flat, level plains and swamplands in the west to irregular rolling hills, cavernous limestone bluffs, and deep river gorges in the central part of the state, to plateau tablelands, broad river valleys, narrow mountain passes, and mountain peaks in the east.

The Interstate parallels the older U.S. Route 70 (US 70) corridor for its entire length in the state. It has interchanges and concurrencies with four other mainline Interstate Highways, and has five auxiliary routes: I-140, I-240, I-440, I-640, and I-840. I-40 in Tennessee was mostly complete by the late 1960s, having been constructed in segments. The stretch between Memphis and Nashville, completed in 1966, was the state's first major Interstate segment to be finished.