Interstate 77 (abbreviated I-77) is an interstate highway in the eastern United States. It traverses diverse terrain, from the mountainous state of West Virginia to the rolling farmlands of North Carolina and Ohio. It largely supplants the old U.S. Highway 21 between Cleveland, Ohio, and Columbia, South Carolina, as one of the best north-south corridors through the middle Appalachians. The southern terminus of Interstate 77 is in Columbia at the junction with Interstate 26. The northern terminus is in Cleveland at the junction with Interstate 90.

The East River Mountain Tunnel is one of only two instances in the United States where a mountain road tunnel crosses a state line. The other one is the Cumberland Gap Tunnel, connecting Tennessee and Kentucky.

I-77 map