The Wellsville, Addison & Galeton Railroad was formed in 1954 to operate a section of Baltimore & Ohio Railroad (B&O) trackage which had been isolated from the rest of the system by a 1942 flood. This trackage was acquired by the B&O as part of the purchase of the Buffalo & Susquehanna Railroad (B&S) in 1932. It is known as the operator of a set of GE centercab diesels supplemented by F7 locomotives in later years.

The Buffalo and Susquehanna Railroad was a railroad company that formerly operated in western and north central Pennsylvania and western New York. It was created in 1893 by the merger and consolidation of several smaller logging railroads. It operated independently until 1929, when a majority of its capital stock was purchased by the Baltimore and Ohio Railroad. At the same time, the B&O also purchased control of the neighboring Buffalo, Rochester, and Pittsburgh Railway. The Baltimore and Ohio officially took over operations of both roads in 1932.