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. Route 21 (US 21) between Cleveland, Ohio, and Columbia, South Carolina, as an important north–south corridor through the middle Appalachian Mountains.

[4] I-77 begins as an eight-lane highway at I-26 in the far southwestern part of the Columbia metropolitan area.

In the Columbia area, I-77 offers access to Fort Jackson before meeting I-20 in the northeastern part of the city.

North of Charlotte, it skirts Lake Norman where it narrows again to four lanes before passing through Huntersville, Cornelius, Davidson, and Mooresville.

A six-mile (9.7 km) portion south of the city is called the General Younts Expressway.

On March 31, 2013, there was a nearly 100-car pileup on I-77 near Fancy Gap; as a result of that crash, electronic variable speed limit signs are now in place along that stretch of I-77.

At milepost 9, I-77 becomes cosigned with the West Virginia Turnpike for the next 88 miles (142 km), a toll road between Princeton and Charleston.

I-77 is also known as the Vietnam Veterans Memorial Highway in Ohio[7] and the Willow Freeway in Greater Cleveland.