US 378 has a length of in Georgia and spans in South Carolina. The U.S. Highway is a part of the
National Highway System from
US 178 in
Saluda east to
US 501 and
US 701 in Conway.
Georgia US 378 begins at an intersection on the eastern edge of the city of Washington with US 78, SR 10, and SR 17, which form the north–south axis of the junction, and US 78 Business, SR 47, SR 10 Business, and SR 17 Business, which heads west on Robert Toombs Avenue toward downtown Washington. US 378 and SR 47 head east on Lincolnton Road, also known as Joe Wheeler Highway, which starts as a four-lane divided highway but becomes two lanes a short distance east of the intersection. Shortly after the
Wilkes–
Lincoln county line, the highways, now part of Washington Highway, meet the western end of
SR 220, a C-shaped route through southern Lincoln County. US 378 and SR 47 gradually curve north and enter the city of Lincolnton as Washington Street. SR 47 splits east from the U.S. Highway and
SR 43 begins to run concurrently with US 378 at their intersection with Elm Street. The highways pass along the west side of downtown Lincolnton and curve northeast, meeting the southern end of
SR 79 (Goshen Street) before leaving the city. US 378 and SR 43 continue northeast on McCormick Highway, which meets the northern end of
SR 43 Connector (Old Petersburg Road) a short distance east of the city limits at Wright's Crossing. The highways cross the Soap Creek branch of the
Savannah River reservoir known as
Clarks Hill Lake in Georgia and
Lake Strom Thurmond in South Carolina.
South Carolina State line to Saluda US 378 and SR 43 meet the eastern end of SR 220 just west of
Elijah Clark State Park. SR 43 reaches its northern terminus at the state line at the
thalweg of the Savannah River in the center of the lake crossing. US 378 enters
Sumter National Forest and crosses the
Little River branch of the lake, on the east side of which is
Baker Creek State Park. The highway continues to the town of McCormick, through which the highway follows Gold Street. US 378 intersects
SC 28 (Mine Street) on the west side of downtown;
US 221 leaves its concurrency with SC 28 coming from
Augusta and joins US 378 through the downtown area. The U.S. Highways have a grade crossing of
CSX's
McCormick Subdivision and diverge on the east side of town, with US 221 heading northeast as Greenwood Highway. US 378 leaves McCormick, passes
McCormick County Airport, and forms the southern boundary of Sumter National Forest east of the town. East of Liberty Hill, where the highway fully enters the national forest, the road crosses the
McCormick–
Edgefield county line. US 378 again forms the southern boundary of Sumter National Forest from its intersection with
SC 67 (Callison Highway). The highway also intersects
US 25 and
SC 430 (Meeting Street Road) while passing along the northern tier of Edgefield County. US 378 leaves the national forest shortly after entering
Saluda County. The highway enters the town of Saluda along Church Street and intersects Main Street, which carries US 178,
SC 39, and
SC 121. Two blocks to the east, US 378 turns north onto Jennings Street, then turns east on Travis Avenue at its junction with
SC 194, which heads north on Jennings Street, and US 178 Connector, which heads west on Travis Avenue to connect with US 178.
Saluda to Sumter US 378 crosses the
Little Saluda River and leaves Saluda along Columbia Highway. After crossing Clouds Creek, the highway meets
SC 391 (Prosperity Highway/Summerland Highway) at a
roundabout and enters
Lexington County. East of the Hollow Creek and Horse Creek branches of
Lake Murray, US 378 expands to a four-lane road with center turn lane. The highway becomes concurrent with US 1 (Main Street) on the western edge of the town of Lexington. After US 1 splits southeast to head to the center of town, US 378 continues on Columbia Avenue, then has a brief concurrency with
SC 6 along Lake Drive. The U.S. Highway exits the town along Sunset Boulevard. US 378 has a
partial cloverleaf interchange with
I-20 and a
single-point urban interchange with
I-26 before entering the city of West Columbia. The highway meets the northern ends of
SC 35 (12th Street) and
SC 12 Connector (9th Street), which provides access to westbound SC 12. East of the connector route, US 378 becomes a four-lane undivided highway. The highway has a partial interchange with SC 12 (Jarvis Klapman Boulevard) that only allows access to and from Columbia. US 378 meets US 1 (Meeting Street) and the northern end of
SC 2 (State Street) just before the two U.S. Highways cross the
Congaree River on the four-lane Gervais Street Bridge into
Richland County and the city of Columbia. The highways follow four-lane divided Gervais Street past
EdVenture and the
South Carolina State Museum and intersect Huger Street, which carries
US 21,
US 176, and
US 321. US 378 and US 1 cross over
Norfolk Southern Railway's
W Line and pass through the
Congaree Vista neighborhood. At the intersection with
SC 48 (Assembly Street), the highways pass between the
South Carolina State House and
Capitol Center. US 378 begins its long concurrency with US 76 when the latter highway turns onto Gervais Street from Bull Street. The three U.S. Highways cross over Norfolk Southern's
Columbia District rail line before reaching Millwood Avenue, where US 1 turns north and US 378 and US 76 turn south. Gervais Street continues east as an unnumbered street several blocks through a residential area before reaching its eastern terminus. US 378 and US 76 follow Millwood Avenue, a four-lane street with center turn lane, southeast to an oblique intersection with Devine Street. Devine Street carries US 21 Connector and US 76 Connector west through
Five Points and the
University of South Carolina campus. The U.S. Highways continue east along Devine Street to their intersection with
SC 16 (Beltline Boulevard), where the road expands to six lanes. A short distance to the east, US 378 and US 76 have an intersection with
SC 760 (Fort Jackson Boulevard), which heads east toward the
namesake military installation, and a second US 76 Connector that follows Cross Hill Road north to SC 16. East of their intersection with a third US 76 Connector, which heads east on Wildcat Road and west on Rosewood Drive, the U.S. Highways continue as Garners Ferry Road. US 378 and US 76 meet the western end of
SC 262 (Leesburg Road) just west of the U.S. Highways' and state highway's partial cloverleaf interchanges with
I-77 (Veterans Memorial Freeway). Southeast of I-77, the road becomes a four-lane divided highway, leaves the city of Columbia, and meet the northern end of
SC 768 (Pineview Road). US 378 and US 76 enter a rural area and pass through
Horrell Hill, where they meet the northern end of
SC 769 (Congaree Road), pass
McEntire Joint National Guard Base, and have a junction with the western end of
SC 764 (Old Eastover Road). The U.S. Highways have a
diamond interchange with
US 601 (McCords Ferry Road) and an intersection with
SC 263 (Vanbloken Road) north of
Eastover before they cross the
Wateree River into
Sumter County.
Sumter to Conway East of the extensive swamp surrounding the Wateree River, US 378 and US 76 pass south of the village of
Stateburg and intersect
SC 261 (Kings Highway). East of
SC 441, Peach Orchard Road/Patriot Parkway), the U.S. Highways enter the city of Sumter, through the western portion of which they follow Broad Street. US 378 and US 76 have a
trumpet interchange with Shaw Drive, the main access to
Shaw Air Force Base, and follow the southern boundary of the military reservation. East of the base, the highways pass through a commercial area and meet the northern end of
SC 120 (Alice Drive) just west of where Broad Street continues along
US 76 Business while the U.S. Highways continue along the Robert E. Graham Freeway. Just east of the business route, US 378 and US 76 have a half-diamond interchange with
US 521 (Camden Highway) allowing access with US 521 to and from the east; the other movements are made via US 76 Business and Jefferson Road. A pair of frontage roads parallels the freeway; the U.S. Highways have
right-in/right-out interchanges with the frontage roads just west of the overpass of
US 15 (Main Street). The frontage roads end at the freeway's diamond interchange with
US 401. US 378 and US 76 cross a rail spur before highways exit the city of Sumter and the frontage roads reappear along the freeway. The U.S. Highways diverge at their partial cloverleaf interchange with the eastern end of US 76 Business (Liberty Street); US 76 heads east as Florence Highway while US 378 continues southeast along the freeway to
East Sumter, where it ends at the eastern terminus of
SC 763 (Myrtle Beach Highway). US 378 continues east as Myrtle Beach Highway, a four-lane divided highway. The highway crosses the
Black River and intersects
SC 527 (Brick Church Road) at McBrides Corner. US 378 has an acute junction with
SC 53 (Narrow Paved Road) and a diamond interchange with
I-95 before entering
Clarendon County, where the route follows Clarence Coker Highway. The highway becomes undivided as it enters the town of
Turbeville. US 378 runs concurrently with
US 301 along four-lane undivided Main Street, which intersects
SC 58 (Gamble Street) one block north of the US 378–US 301 junction. The two U.S. Highways split near the northern end of town, with US 378 continuing east as a four-lane road with center turn lane. The highway enters
Florence County, where its name changes to Turbeville Highway, then returns to the county line and runs atop the southern boundary of Florence County. During this stretch, the county to the south of the highway becomes
Williamsburg County. Soon after US 378 fully enters Florence County, the highway intersects
SC 341 (Olanta Highway). The two highways briefly run together before SC 341 continues straight concurrent with US 378 Business on Lake City's Main Street while US 378 splits northeast to bypass Lake City. North of the town, the U.S. Highway has a diamond interchange with
US 52 (Ron McNair Boulevard). US 378 crosses over CSX's
Charleston Subdivision before collecting the eastern end of US 378 Business (Myrtle Beach Highway). US 378 continues northeast as Myrtle Beach Highway. The highway crosses the
Lynches River and curves southeast and then east through the hamlet of
Hannah.
SC 51 (Pamplico Highway) joins US 378 on a tangent curve at Salem and follows the U.S. Highway east to Kingsburg, where SC 51 turns south onto Kingsburg Highway and
SC 41 joins the U.S. Highway as it curves northeast U.S. Highway 378 reduces to two lanes near Capitola Road in Johnsonville. and crosses the
Great Pee Dee River into
Marion County. The two highways curve southeast and cross over CSX's
Andrews Subdivision before SC 41 splits to the north on a tangent curve. The U.S. Highway meets the southern end of
SC 908 south of
Brittons Neck before it curves east and crosses the
Little Pee Dee River into
Horry County. US 378 expands to a four-lane road with center turn lane shortly after passing
Conway-Horry County Airport and enters the city of Conway as Wright Boulevard. West of downtown, the U.S. Highway has an oblique intersection with Church Street, which carries US 501 through the intersection and US 701 north of the intersection. Southbound US 701 continues south on Church Street to a ramp to 4th Avenue while northbound US 701 runs concurrently with US 378 from 4th Avenue, which heads west as US 701 toward
Georgetown and east as
SC 905. US 378 curves northeast, becomes 3rd Avenue, and reduces to two lanes as it enters the
Conway Downtown Historic District, where it reaches its eastern terminus at US 501 Business (Main Street) next to the
Old Conway County Courthouse. ==History==