The Tennessee state routes do not follow a systematic numbering system unlike the U.S. Highway System and some other states' highway systems. The routes are separated into primary and secondary routes though. Many of the routes are hidden in that they are overlaid on U.S. Routes and not signed. The mile markers throughout Tennessee, however, show the state route number for these hidden routes.
The Tennessee Department of Transportation (TDOT) maintains these routes under the "State Highways" title of state law,[1] but designates them as "state routes". The triangle marker design was the only design until November 1983, when Tennessee divided its routes into primary routes and secondary or "arterial" routes with the adoption of a functional classification system, creating a primary marker and making the triangle marker the secondary marker; primary marker signs were posted in 1984.[2]
Proposed by 1986 but never built; shown in the document as TN 399, which was probably not the designation for this road because the current one was created around the same time[5]
Former portion of SR 34; decommissioned when US 421 was rerouted off of this road; now MLK Jr Boulevard; still on official maps through 2017, but off functional maps by 2014
Proposed I-75 bypass of Knoxville, also proposed to be extended to I-40 at exit 407 (SR 66) to provide a complete northern beltway of Knoxville and provide a more direct route to Sevier County/Great Smoky Mountains National Park
^"New Name For State Highway". Kingsport News. May 7, 1966. p. 17. Retrieved November 14, 2023 – via Newspapers.com.
^ abTennessee Department of Transportation (March 1986). "Urgent Highway Needs"(PDF). Tennessee Department of Transportation.
^Long Range Planning Division (2017). Knoxville(PDF) (Map). Scale not given. Nashville: Tennessee Department of Transportation. Archived from the original(PDF) on October 16, 2017. Retrieved August 7, 2017.
