South Carolina Highway 121 (SC 121) is a 134.200-mile (215.974 km) major state highway that travels north and south in central parts of the U.S. state of South Carolina. The highway is actually part of a long multi-state highway that also exists in Florida and Georgia, as Florida State Road 121 and Georgia State Route 121, respectively.

Augusta is a consolidated city-county on the central eastern border of the U.S. state of Georgia. The city lies directly across the Savannah River from North Augusta, South Carolina at the head of its navigable portion. Georgia's third most populous city, Augusta is located in the Fall Line section of the state.