US 1 enters South Carolina in
North Augusta, along an
expressway with
US 25,
US 78, and
US 278 on a bridge over the
Savannah River from
Augusta, Georgia.
South Carolina Highway 121 (SC 121) also begins at the state border. The expressway is known locally as the
Jefferson Davis Highway. At the second interchange (E. Martintown Road), US 25 and SC 121 leave the expressway. After several at-grade intersections, there is an interchange with
I-520, and the route bypasses the
Aiken County communities of
Clearwater (where US 278 leaves the concurrency),
Burnettown, and
Gloverville. Upon entering the city of
Aiken, the three
concurrent routes transition to a boulevard with a center turn and turns from a northeasterly direction to a more directly eastbound direction. This area is heavily developed, with shopping centers and subdivision entrances along both sides of the road. The road is known locally as Augusta–Aiken Road. Reaching the historic central area of Aiken, the route turns to a divided road again as the name changes to Richland Avenue, and the route becomes heavily residential with a wide, tree-lined median down the middle. US 1 leaves Richland Avenue and US 78 to turn north on York Street. York Street is a four-lane boulevard until it meets Hampton Avenue, where it leaves the main grid of central Aiken and becomes a five-lane boulevard with a center turn lane through a light industrial area leading north out of the city. Leaving Aiken, it is known as the Columbia Highway and passes
Aiken Regional Airport and an interchange with I-20 north of the city, after which the road narrows to a two-lane rural highway. It passes into
Saluda County in
Moneta, and then on through the town of
Batesburg-Leesville as Columbia Avenue, where it gains a center turn lane. It meets the eastern terminus of
SC 23 at the eastern edge of town and loses its center turn lane as the name changes to Augusta Highway. Passing through a large rural area, the road once again widens to a five-lane boulevard with a center turning lane as it approaches
Lexington. Entering Lexington, the road merges with
US 378 along West Main Street. US 378 then leaves West Main Street along Columbia Avenue. West Main Street changes to East Main Street at Lake Drive (
SC 6 and changes names again to Augusta Road about before a second interchange with I-20. US 1 passes east–west through the communities of
Oak Grove and
West Columbia before crossing the
Congaree River along the Gervais Street Bridge. Shortly before the bridge US 378 merges once again with US 1. After the river, US 1 goes through downtown
Columbia along Gervais Street, passing directly in front of the
South Carolina State House. At Millwood Avenue, US 1 turns northeast while US 378 leaves to the southeast on the same road. Crossing
SC 12 (Taylor Street/Forest Drive), the name changes to Two Notch Road, named for when the road was marked by posts with two notches carved. Passing the
Columbia Place shopping mall, it has a third interchange with I-20 and passes through several unincorporated Columbia suburbs in
Richland County. An interchange with Clemson Road provides access to I-20 and to
Fort Jackson. Entering
Kershaw County, US 1 merges with
US 601 in
Lugoff and, crossing the
Wateree River, enters
Camden along DeKalb Street. US 601 leaves at the center of Camden. From Camden, it continues northeast as a two-lane road through several small towns of the Sandhills region, merging with
US 52 between
Cheraw State Park and the town of south of
Cheraw. Within Cheraw, it follows Market Street (where
SC 9 joins) then Second Street and turns onto Powe Street (while US 52 continues on Second Street). US 1 turns north on its own routing while SC 9 continues west. Approximately north of Cheraw, US 1 enters
North Carolina. The entire route is part of the Jefferson Davis Highway, named after
Civil War Confederate leader
Jefferson Davis; with exception between North Augusta and Aiken, where US 1 was realigned, leaving
SC 421 its section of the highway name. Markers of the highway dot all along the route, though most sections do have other road names too. ==History==