Interstate 20 (I-20) is the main east–west Interstate Highway in the state of South Carolina, linking the state with important transportation and business hubs to the north, west, and south, including Atlanta, Georgia; Charlotte, North Carolina (via I-77); Savannah, Georgia (via I-95); and Washington, D.C. (via I-95). I-20 travels west to east, from the Georgia state line at North Augusta, through Columbia, to end at I-95 in Florence.

Beyond its eastern terminus at I-95, the roadway continues as I-20 Business (I-20 Bus.) for about to U.S. Route 76 (US 76), which goes to downtown Florence.

The Interstate parallels US 1 closely from the state line to Camden where US 1 diverts away from the route and head northeast towards Rockingham, North Carolina while I-20 turns and heads eastward towards Florence.

Route description From North Augusta to Columbia

I-20 enters the Palmetto State of South Carolina as a continuation of six lane freeway after crossing the Savannah River from Augusta, Georgia. I-20 is known as the J. Strom Thurmond Freeway (named for the US senator) for its entire length in the state. I-20 immediately enters the North Augusta city limits after crossing from the Georgia border. Soon, the eastbound lanes gets access to South Carolina welcome center, before meeting interchange with South Carolina Highway 230 (SC 230 / West Martintown Road), which goes to downtown North Augusta. I-20 narrows to four lanes as it passes below this interchange. I-20 passes north of North Augusta for before meeting an interchange with U.S. Route 25 (US 25)/SC 121 (Edgefield Road) that goes through downtown of the city, but also connecting to Edgefield and Johnston. US 25 links I-20, north to Greenville. Then immediately meeting the eastern terminus of I-520 (Palmetto Parkway) about half-mile later. I-520 serves as a partial-beltway bypassing North Augusta westward to later bypass Augusta, Georgia.

I-20 leaves the city limits of North Augusta as it continues going northeast to pass city of Graniteville, crossing over SC 191 without an interchange before passing two Aiken exits. I-20 meets an interchange with SC 19 that connects to the city of Aiken. I-20 passes with access to the truck commercial parking before meeting the first interchange (out of three) with US 1, that also provides to city of Aiken. From here, US 1 begins parallel I-20 through most its route til passing Camden.

I-20 leaves Aiken as it meets an interchange with Wire Road linking to the northern beginning of SC 391 toward Batesburg-Leesville. I-20 meets an interchange with SC 39, that connects to Monetta, Ridge Spring, and Wagener. I-20 passes the weigh station, only access from the eastbound lanes before meeting an interchange with US 178, that connects to Pelion and also to Batesburg-Leesville. I-20 later meets Road 34 (Pond Branch Road), which serves to Gilbert.

At the south of Gilbert, after passing a pair of closed rest areas, I-20 widens to six lanes before meets an interchange with Longs Pond Road. After passing with access to the weigh station for the westbound lanes, I-20 leaves the Gilbert community and enters Lexington to meet an interchange with SC 6 (South Lake Drive). The westbound lanes have two exits for SC 6, which exit 55A exits to SC 6 east toward Swansea (signed as Pelion (via SC 302 west from SC 6); although SC 6 doesn’t directly go there) while exit 55B exits to SC 6 west toward downtown Lexington. I-20 curves to the north, crossing over the Norfolk Southern Railroad tracks before meets its second interchange with US 1 (Augusta Road), linking to the Columbia Airport along with the cities of West Columbia, and also to downtown Lexington. I-20 curves back to northeast to have an interchange with US 378 (Sunset Boulevard), which connects to Lexington and West Columbia. US 378 links I-20 to Athens, Georgia via along US 78 from its western terminus in Washington, Georgia.

I-20 crosses the Saluda River before meeting an interchange with Bush River Road. I-20 widens temporarily to eight lanes before immediately meeting its Malfunction Junction cloverleaf interchange with I-26/US 76 (James F. Byrnes Memorial Freeway), that goes northwest to Spartanburg and southeast to Charleston. I-26 indirectly goes northwest to Greenville via I-385 north. I-126 begins east at I-26, about a mile southeast of I-20, goes eastward with US 76 toward downtown Columbia. During crossing the below the I-26/US 76 interchange, I-20 leaves city limits of Lexington and West Columbia while entering the capital of the city limits of Columbia. SCDOT is currently working on reconstruction the cloverleaf interchange to being reconfigured into turbine interchange, removing the loop ramps, and soon adding a direct ramp from I-20 to I-126 east without merge onto mainline I-26. I-20 narrows back to six lanes, then meets its DDI interchange with US 176 (Broad River Road), shortly after the I-26/US 76 interchange. During crossing below US 176 interchange, I-20 temporarily widens back to eight lanes additionally with three right exit lanes on the westbound lanes for US 176 and westbound I-26/US 76. I-20 is planned to be widened into eight lanes with exit lanes from US 176, westward to US 378.

From Columbia to Florence

I-20 narrows back to six lanes as it crosses the Broad River. I-20 passes north of Columbia to meet its next interchange with SC 215 (Monticello Road), which goes northward to the city of Jenkinsville. Then a mile later, I-20 meets an interchange of US 321 (Fairfield Road), which goes northward to the city of Winnsboro. US 321 links I-20, northward to Gastonia, North Carolina. I-20 continues for another mile to meet an interchange with US 21 (North Main Street). US 21 serves as a parallel route for I-77, north of Columbia. I-20 meets two interchanges with SC 555 (Farrow Road) before immediately meeting SC 277. SC 277 northbound connects to I-77 northbound toward Charlotte, North Carolina. I-20 soon meets its third and final interchange with US 1 (Two Notch Road). From here, US 1 remains paralleling north of I-20 until passing Camden. I-20 crosses over an unnamed lake before meeting interchanges with I-77 and Alpine Road. I-77 south goes back to I-26 since I-77, I-26, and I-20 altogether serve as a beltway loop around Columbia. I-20 eastbound has no direct exit to I-77 northbound, so drivers on I-20 east must use the Alpine Road exit as a u-turn method to get on I-77 north.

After its interchanges with I-77 and Alpine Road, I-20 leaves the city limits of Columbia as it passes through the north of Fort Jackson while beginning to parallel north of SC 12 (Percival Road). I-20 meets the interchanges with Clemson Road and Spears Creek Church Road, south of Pontiac before narrowing back to four lanes. It later meets an interchange with White Pond Road, that connects to the small town of Elgin before reaching Luggoff.

In Luggoff, I-20 meets an interchange with US 601 and eastern terminus of SC 12 before a mile later passing with access to the rest area. I-20 curves to the east as it crosses over Buck Creek and the Wateree River before meeting an interchange with US 521 in Camden. US 521 provides access to Sumter. Shorty after this interchange and passing Camden, US 1 stops paralleling I-20 as it goes to its own way to northeast through the Sandhills region toward Rockingham, North Carolina.

I-20 passes the small town of Antioch. As SC 34 gets closer to the route, I-20 meets an interchange with Jamestown Road; a connector road to SC 34, and to the town of Manville. SC 34 goes further away from I-20 as it goes toward Bishopville. I-20 passes the town of Browntown before meeting the interchanges of US 15, and then SC 341 near Bishopville, which both routes go northward to. I-20 cross below SC 154 without an interchange between both of its interchanges with US 15 and SC 341. South of I-20, US 15 goes southwest as another way to go to Sumter while SC 341 goes southeast toward Lynchburg. I-20 crosses over the Lynches River through the marshes as it passes south of the Lee State Park before meeting an interchange with Lee State Park Road, that connects to the state park entrance.

I-20 continues passing with access to a parking area for commercial vehicles only. Then crossing over SC 403 without an interchange before meeting an interchange with US 401 near Lamar, that connects to SC 403 and the cities of Timmonsville (via SC 403 south), Darlington, and also goes to Sumter. I-20 later meets an interchange with SC 340 that also goes to Timmonsville and Darlington. I-20 continues its final passing south of Darlington before reaching Florence.

As I-20 approaches towards the city of Florence, it meets its eastern terminus at an interchange with I-95. At this interchange, the main travel lanes of I-20 defaults to exit left on exit 141A to merge onto the lanes of I-95 north toward Fayetteville, North Carolina. After passing exit 141A, I-20’s right exit 141B to I-95 south goes southwest from Florence towards Savannah, Georgia. But in 2025, SCDOT moved I-20 eastbound’s mile maker 141 sign to the left exit ramp of exit 141A, and changed I-20 eastbound’s exit 141A sign with the arrow pointing left to the exit 141B sign with the arrow pointing right. Treating it as if I-20 now continues past the I-95 south (along with I-20 Bus. east) exit before curving northeast to meet its eastern terminus when its lanes merges onto I-95’s northbound lanes. SC 327 (along with US 76, SC 576, and US 501) serves a connection to Myrtle Beach from I-20’s eastern terminus via I-95 north. Beyond this interchange, the roadway continues for towards downtown Florence as I-20 Bus. eastbound (David H. McLeod Boulevard east).

Services The South Carolina Department of Transportation (SCDOT) operates and maintains one welcome center and two rest areas along I-20. The welcome center, which has a travel information facility on site, is located in North Augusta at milemarker 0.5 (eastbound), and the rest areas are located in Lugoff at milemarker 99 (east and westbound) between exit 92 (U.S. Route 601 [US 601] and SC 12) and the bridges over the Wateree River. Common at all locations are public restrooms, public telephones, vending machines, picnic area, and barbecue grills. A pair of closed rest areas exist between exits 44 and 51.

The South Carolina Department of Public Safety and State Transport Police operate and maintain two truck inspection/weigh stations. The eastbound truck weigh station can be found in Jones Crossroads at milemarker 35, and the westbound weigh station can be found in Lexington at milemarker 53.5.

History

I-20 first appeared between 1964 and 1967; its first section was completed from SC 6, south of Lexington, to Spears Creek Church Road (S-40-53), south of Pontiac. A second section, from the Georgia state line to US 25/SC 121, was completed in 1967. In 1968 or 1969, I-20 was extended east from Spears Creek Church Road (S-40-53) to US 601/SC 12, south of Camden. In 1971, I-20 combined the two segments by completing the gap between US 25/SC 121 to SC 6. In 1973, I-20 was extended east to US 521. In 1974, it extended east again to US 15. In 1975, another extension east to US 401 with the final section between SC 340 and I-20 Bus. opening in August 1975. And finally, in 1976, I-20 reached its destination with I-95 and the city of Florence. Also in the same year, exit numbers were installed.