Interstate 640

I-640 begins at an interchange with I-40 and I-75, where I-75 continues onto I-640. Initially heading northwest, I-640 and I-75 turn northeast, intersecting SR 62 before coming to an interchange with SR 9, US 25W, I-75, and I-275. As the freeway continues, US 25W and SR 9 run concurrently for the rest of its length, but are not signed. I-640 interchanges with SR 33 and US 441, as well as one providing access to the Knoxville Center Mall. The highway then turns south and terminates at I-40. At this interchange, US 25W continues onto an unsigned concurrency with I-40 to the east. I-640 also crosses US 11W directly north of its eastern terminus, but does not have an interchange with this route.[2]

In December 1970, the 2.2 miles (3.5 km) segment between I-75/275/US 25W (Clinton Highway) and US 441 (Broadway/Old Broadway) was opened. This was the only section of I-640 that was open for some time.[3] The 3.5 miles (5.6 km) section between I-40/75 and I-75/275 opened on December 23, 1980.[4][5] In April 1982, the road was finally completed in anticipation of the traffic which was to be generated by the 1982 World's Fair. Then Governor of Tennessee, now United States Senator Lamar Alexander officially opened the road by walking its entire length dressed in his famous red plaid shirts that he famously wore during his both of his campaigns for Governor of Tennessee. I-75 originally ran concurrent with I-40 to downtown Knoxville, but was moved out of the section between I-40 and I-75 through Sharp's Gap to the approximately 2.5 miles (4.0 km) section of I-640 between I-40 and I-75 in 1982.[6] This section is only signed as I-640, and the exits on this section follow I-640 numbering. In May 2008, a complete redesign near I-40 east of downtown added lanes, reconfigured exits, and improved safety closed that section of I-40 for 13 months. The road construction project was officially called Smart Fix 40, and the Tennessee Department of Transportation closed that section of I-40 until June 2009, when it was officially completed 18 days early. During the course of the Smart Fix 40 construction project, the Tennessee Department of Transportation used I-640 as the official detour route for I-40 traffic during the time in which I-40 was closed for the reconfiguration.[7]

The entire route is in Knoxville, Knox County.

mi	km	Exit	Destinations	Notes
0.00	0.00		I-75 south / I-40 west – Nashville, Chattanooga	Western terminus; western end of I-75 concurrency; I-40 exit 385
		—	I-40 east – Knoxville	Westbound left exit and eastbound entrance; I-40 exit 385
0.6	0.97	1	SR 62 (Western Avenue)
2.3	3.7	3B	To US 25W north (SR 9 north) / Gap Road – Clinton	Eastbound exit only
2.9	4.7		US 25W north (SR 9 north) – Clinton	No eastbound exit; western end of US 25W/SR 9 concurrency
		3A	I-75 north / I-275 south – Knoxville, Lexington	Eastern end of I-75 concurrency; I-275 exit 3
5.4	8.7	6	US 441 (Broadway / SR 33 / SR 71) / Old Broadway (SR 331)	Old Broadway signed eastbound only
7.6	12.2	8	Washington Pike / Mall Road / Millertown Pike	Partially signed as Mall Rd. South eastbound, Mall Rd. North westbound
10.1	16.3	10B	I-40 west – Nashville	Eastbound exit and westbound entrance; I-40 exit 393
		10A	I-40 east (US 25W / SR 9 south) – Asheville	Eastern terminus; eastern end of US 25W/SR 9 concurrency; I-40 exit 393
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus       Incomplete access