The state highway runs 89.79 miles (144.50 km) from U.S. Route 15 (US 15) in Dillwyn north to SR 3 in Wilderness.

The state highway heads north as the two-lane undivided Constitution Route, which passes through the hamlet of Allenslevel, the site of Buckingham Correctional Center.

SR 20 passes the entrance to Piedmont Virginia Community College just south of its partial cloverleaf interchange with Interstate 64.

The business route joins SR 20 in a concurrency on High Street, which passes by the former Martha Jefferson Hospital.

SR 20 turns east onto US 250 to cross the Free Bridge over the Rivanna River to leave the city limits.

[1][3] SR 20 heads north from the Charlottesville vicinity along Stony Point Road, which parallels the west flank of the Southwest Mountains.

The state highway passes the communities of Key West, Eastham, Stony Point, and Rosena.

SR 20 enters Orange County and its name changes to Constitution Highway south of Barboursville, which contains the ruins of the namesake estate.

The state highway turns east onto Berry Hill Road and passes under another Norfolk Southern rail line before receiving the other end of SR 20 Business (Byrd Street).

SR 20 briefly passes through part of Fredericksburg and Spotsylvania National Military Park near the site of the Battle of the Wilderness before reaching its northern terminus at SR 3 (Germanna Highway) in the community of Locust Grove just west of the Spotsylvania County line.

The business route intersects US 15 (Madison Street) and meets Norfolk Southern Railway's Washington District at grade.