Known as Van Dorn Street (Lincolnia Road until 1953[2]), the state highway runs 2.61 miles (4.20 km) from SR 613 at the south city limit of the independent city of Alexandria north to SR 420 within Alexandria.

SR 401 begins at the south city limit of Alexandria, which is located on the north side of the underpass of CSX's RF&P Subdivision.

Van Dorn Street continues south as SR 613 into Fairfax County toward its interchange with Interstate 95 (I-95)/I-495 (Capital Beltway) and Franconia.

SR 401, which heads north as a four-lane divided highway, has an intersection with Eisenhower Avenue, an east–west arterial through the industrial southern edge of Alexandria, and has a trumpet interchange with a connector to Eisenhower Avenue and the Van Dorn Street station on the Washington Metro's Blue Line.

The state highway crosses over Norfolk Southern Railway's Washington District and Backlick Run and intersects Edsall Road.