Interstate 640 encircles central Knoxville to the north. The freeway bypasses Downtown and the University of Tennessee.
Interstate 640 through Knoxville is an urban loop serving both long distance and freight traffic along I-40 and I-75 north to Kentucky. Additionally the bypass is the mandatory route for trucks carrying hazardous materials across the city. Varying between four and six lanes, I-75 accompanies I-640 along the arc south from I-275 at Inskip to I-40 by Marble City. I-640 measures 10.8 miles in length, but only the portion east of I-75 is attributed to it within the FHWA Route Log and Finder List.
Construction for the Knoxville northern bypass commenced October 1977 with a completion date of April 1982. Interstate 75 was relocated to bypass Downtown Knoxville along side I-640 in 1982. The former alignment was renumbered Interstate 275.