The Chessie System was a holding company developed by the Chesapeake & Ohio Railway to hold the stock of railroads it acquired. The C&O gradually merged these railroads into a system known today as CSX, which remains a major force in West Virginia's economy and transportation network.

In the years after World War II, the C&O attempted to acquire a number of railroads with only modest success. The Norfolk & Western, a major rival, was more successful, as it acquired the Virginian, the Nickel Plate, and the Wabash railroads in the late 1950s. In an effort to keep up, the C&O acquired the Baltimore & Ohio in 1960 and the closely aligned Western Maryland in 1964.

The merger of the C&O, the B&O, and the Western Maryland proceeded slowly. In 1972, the new president of the C&O-B&O, Hays T. Watkins Jr., announced the creation of the Chessie System (incorporated in 1973), which included the three railroads. Although operated as one, the three maintained separate corporate identities until 1976.

The Chessie System's logo was an outline of a sleeping cat, named Chessie, embedded in a blue circle. For many years Chessie had been the mascot of the C&O and had appeared on calendars, timetables, and advertisements produced by the railroad. This logo helped to maintain the image of the C&O within the merged system.