State Route 55 (SR 55) is a primary state highway in the U.S. state of Virginia. Known for most of its length as John Marshall Highway, the state highway runs 64.71 miles (104.14 km) from the West Virginia state line, where the highway continues as West Virginia Route 55 (WV 55), east to U.S. Route 29 (US 29) in Gainesville. West of its interchange with Interstate 81 (I-81) in Strasburg, SR 55 runs concurrently with the easternmost portion of US 48 as part of Corridor H.