U.S. Route 129 is a north–south United States highway that runs for 52.8 miles (85.0 km) from the North Carolina state line, near Tapoco, to Knoxville.

US-129 enters Tennessee through Deals Gap, where it twists and turns along the Little Tennessee River. This section is known as the Tail of the Dragon, popular to driving enthusiasts (of motorcycles and sports cars). At Clover Hill, US-129 joins US-441 to Maryville; from this point US-129 continues on as a 4-lane highway/expressway. Bypassing east around Maryville and Alcoa, it connects with Pellissippi Parkway (I-140) before entering Knoxville, where it ends at I-40. SR-115 is the hidden state route that overlaps the entire route.