The PATrain, also known as the Mon Valley Commuter Rail, is a defunct commuter rail service formerly operated by the Port Authority of Allegheny County in the Monongahela Valley. Service began in 1975 when the Port Authority assumed control of the Pittsburgh—McKeesport—Versailles commuter trains operated by the Baltimore and Ohio Railroad (B&O) (part of the Chessie System). The Port Authority discontinued the service in 1989.

The PATrain, also known as the Mon Valley Commuter Rail, is a defunct commuter rail service formerly operated by the Port Authority of Allegheny County in the Monongahela Valley. Service began in 1975 when the Port Authority assumed control of the Pittsburgh—McKeesport—Versailles commuter trains operated by the Baltimore and Ohio Railroad (B&O) (part of the Chessie System). The Port Authority discontinued the service in 1989.