The Western Maryland Railway was an American Class I railroad which operated in Maryland, West Virginia, and Pennsylvania. It was primarily a coal hauling and freight railroad, with a small passenger train operation. The WM became part of the Chessie System in 1973, although it continued independent operations until May 1975 after which time many of its lines were abandoned in favor of parallel Baltimore and Ohio Railroad lines. In 1983 it was fully merged into the Baltimore & Ohio Railroad, which later was also merged into the Chessie System with the former Chesapeake and Ohio Railroad, which is now CSX Transportation.