U.S. Route 321 (US 321) is a spur of U.S. Route 21. It runs for from Hardeeville, South Carolina to Lenoir City, Tennessee; with both serving as southern termini. It reaches its northernmost point at Elizabethton, Tennessee. Because of its unusual "north–south–north" routing, U.S. Route 321 intersects both Interstate 40 and U.S. Route 70 three separate times. The highway serves different roles in each state: An alternate route to interstates in South Carolina, a major highway in North Carolina, and a scenic route in Tennessee. Route description |- |SC |217.2 |349.5 |- |NC |105.5 |169.8 |- |TN |194.2 |312.5 |- |Total |516.9 |831.8 |} South Carolina US 321 provides direct access between Savannah and Columbia, serving as an alternate to Interstate 95 and Interstate 26. Starting in Hardeeville, US 321 as a mostly 2 lane highway goes through sparsely populated areas and small towns including Estill, Fairfax, and Denmark, heading in a rather straight and northward direction into the Columbia area, widening to a 5 lane highway right after Neeses, then narrowing down to a 2 lane highway right after the town of North and widening to a 5 lane highway again after Swansea and staying that way until it merges with its parent route US 21 in Dixiana. In Columbia, the route stays concurrent with US 21 through Cayce, over the Congaree River on the Blossom Street Bridge, turning left onto Huger Street, right onto Elmwood Avenue, and left onto North Main Street. The roads separate at Hyatt Park, with US 321 staying west of I-77 and US 21 north of Columbia. The route goes through to communities of Winnsboro, Chester, York, and Clover before entering North Carolina at Bowling Green. North Carolina US 321 is an important route in Western North Carolina. It provides an alternative north–south route to I-77, which passes through a busy metropolitan area, and US 221, which is more twisty drive up the Appalachians. Travelers from South Carolina who are going to points west of Charlotte and want to avoid the traffic of I-77 may choose to enter the state on US 321. The highway traverses through seven counties: Gaston, Lincoln, Catawba, Burke, Caldwell, Watauga, and Avery. US 321 has six control cities: Gastonia, Lincolnton, Hickory, Lenoir, Blowing Rock, and Boone. US 321 is a multilane highway beginning at the state line. After , it enters the Gastonia area. Traffic on northbound 321 through