Interstate 77 is a north - south interstate highway, extending 91.2 miles (146.8 km) in the state of South Carolina, extending from the national southern terminus at an interchange with Interstate 26 near Columbia, north to the North Carolina state line near Rock Hill and Charlotte, NC.

Interstate 77 begins its journey in Cayce - south-southwest of Columbia - as a six-lane highway at an expansive interchange with Interstate 26 (without an exit number), with the Columbia skyline visible from this interchange. Part of the Columbia Beltway, the highway actually travels eastward from I-26 before turning more to the north in Columbia southwest of Fort Jackson. From Interstate 20 (exit 16), I-77 travels northward paralleling U.S. 21 through the hilly Midlands region, bypassing Winnsboro and Chester. As the highway approaches York County, it enters the Piedmont terrain. It is in York County where I-77 enters the Charlotte metropolitan area, which is evident as the highway widens from four to eight lanes. I-77 continues through the suburbs of Charlotte, passing through Rock Hill and bypassing Fort Mill before crossing the North Carolina border near the Carowinds theme park.

Though the highway is commonly known as "Interstate 77" or "I-77" throughout the state, the highway does have other known names it uses locally in areas.

Interstate 77 is the current route in South Carolina and has forced the decommissioning of Interstate 326. Interstate 77 interchanges with Interstate 20 and Interstate 26 near and at its southern terminus, respectively. There is no beltway in Columbia; Interstate 77, Interstate 20 and Interstate 26 provide bypasses, while Interstate 126 and South Carolina 277 provide downtown access.