Interstate 40 in Tennessee

Interstate 40
I-40 highlighted in red
Route information
Maintained by TDOT
Length	455.28 mi[1] (732.70 km)
Existed	August 14, 1957[2]–present
History	Original route completed September 12, 1975[3] Present-day route completed March 28, 1980[4]
NHS	Entire route
Major junctions
West end	I-40 at the Arkansas state line in Memphis
Major intersections	I-240 / Sam Cooper Boulevard in Memphis I-269 / SR 385 in Arlington I-840 near Burns I-440 in Nashville I-65 in Nashville I-24 in Nashville I-840 in Lebanon I-140 in Knoxville I-75 / I-640 in Knoxville I-81 in Dandridge
East end	I-40 at the North Carolina state line near Hartford
Location
Country	United States
State	Tennessee
Counties	Shelby, Fayette, Haywood, Madison, Henderson, Carroll, Decatur, Benton, Humphreys, Hickman, Dickson, Williamson, Cheatham, Davidson, Wilson, Smith, Putnam, Cumberland, Roane, Loudon, Knox, Sevier, Jefferson, Cocke
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future Tennessee State Routes Interstate US State
← SR 39 → SR 40

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.^[1] The highway crosses Tennessee from west to east, from the Mississippi River at the Arkansas border to the Blue Ridge Mountains at the North Carolina border. 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.^[5]

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.^[6]

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. The last planned section was completed in 1975, and much of the route has been widened and reconstructed since then.

The I-40 corridor between Memphis and Nashville is known as Music Highway because it passes through a region which was instrumental in the development of American popular music. In Memphis, the highway is also nationally significant due to a 1971 U.S. Supreme Court case which established the modern process of judicial review of infrastructure projects. Community opposition to the highway's proposed routing through Overton Park led to a nearly-25-year activist campaign which culminated in the case. This resulted in the state abandoning the highway's original alignment and relocating it onto what was originally a section of I-240.