West Virginia Route 51 is a state highway that runs west to east from Berkeley County to Jefferson County in West Virginia's Eastern Panhandle. The western terminus is at WV 45 northwest of Gerrardstown. The eastern terminus is at an interchange with U.S. Route 340 and WV 9 east of downtown Charles Town. US 340 continues to the east on the same roadway as WV 51.

Berkeley County is located in the Shenandoah Valley in the eastern panhandle region of West Virginia in the United States. The county is part of the Hagerstown–Martinsburg metropolitan area. As of the 2020 census, the county population was 122,076, making it the second-most populous of West Virginia's 55 counties, behind Kanawha County. The City of Martinsburg is the county seat.