U.S. Route 21 or U.S. Highway 21 (US 21) is a major north–south United States Numbered Highway in the Southeastern United States that travels . The southern terminus is in Hunting Island State Park, South Carolina, south of the junction with US 21 Business and South Carolina Highway 802 (SC 802) in Beaufort. The northern terminus is in Wytheville, Virginia at an interchange with Interstate 81 (I-81) and US 52. Despite the "1" indicating that it is a major north-south highway, U.S. 21 only travels through three states, and is no longer a cross-country route as it has been replaced with Interstate 77 in both Ohio and West Virginia. It also has the second-shortest length of all of the major north-south routes, just behind U.S. 91. The route travels through the states of South Carolina, North Carolina, and Virginia. It also connects through major Southeastern cities such as Columbia, South Carolina and Charlotte, North Carolina. The northern portion of the road travels parallel to I-77 in northern South Carolina and North Carolina. The road also has three interchanges with I-26 in Lexington and Calhoun counties in South Carolina. Route description South Carolina US 21 travels through the state. Beginning at Hunting Island State Park, US 21 travels west toward Beaufort, where it widens to four lanes. The route bypasses Beaufort to the south, going through Port Royal, Shell Point, and Burton. In the Beaufort area, US 21 passes by the entrances to Parris Island and MCAS Beaufort, the major Marine Corps installations in the area. North of Beaufort, US 21 continues as a four-lane divided highway and intersects with US 17. The route travels in a wrong-way concurrency with US 17 south for before turning north towards Yemassee, South Carolina, where it becomes a rural two-lane road and intersects with US 17 Alternate. North of Yemassee, US 21 splits off and crosses I-95 at exit 42. The two-lane route continues through rural portions of the state. US 21 goes through Smoaks and Branchville, South Carolina and bypasses Orangeburg. North of Orangeburg, US 21 runs roughly parallel to I-26 until Gaston where it conjoins US 321 and becomes an urban highway. US 21 passes through Cayce, West Columbia, and Columbia. North of Columbia, US 21 splits from US 321, reverting to a rural two-lane road parallel to I-77. In York County, US 21 enters urban areas again, connecting Rock Hill and