CSX Transportation operates several rail lines through the valley, including the old Baltimore and Ohio Railroad, the old Manassas Gap Railroad and the old Virginia Central Railroad. There are also more modern lines that run the length of the valley parallel to the Valley Pike and U.S. 340. The rail lines are primarily used for freight transportation, though Maryland Area Rail Commuter (MARC) trains utilize the old B&O line from stations in Martinsburg, Duffields, and Harper's Ferry to Washington Union Station and vice versa.