The Monongahela Railway (reporting mark MGA) was a coal-hauling Class II railroad in Pennsylvania and West Virginia in the United States.

The primary connection to both controlling systems was at Brownsville, Pennsylvania - with the south end of the P&LE's Pittsburgh, McKeesport and Youghiogheny Railroad and with the PRR's ex-Brownsville Railway.

"As early as 1883, the Pittsburgh, Virginia & Charleston Railway served Brownsville as evidenced by an old lithograph of the Three Towns showing a diamond stacked locomotive coupled to four passenger cars, ready for a northward move, sitting on the track close to the Snowden House and the United States Post Office.

The newly formed Monongahela Railroad acquired many lines in the area from the PV&C as well as the Southwest Pennsylvania Railway Company, as well as the 19 mile (30 km) right of way from Brownsville to Adah from the PRR, for the sum of $519,696.13.

In 1905 the Dunlap Creek branch opened, serving several mines and coke works and also connecting with the Baltimore and Ohio Railroad.

In 1927 the Baltimore and Ohio railroad acquired 1/3 (1/6 from each the PRR and P&LE) of the capital stock of the Monongahela Railway, securing their interests in the coal-producing area it served.

On May 1, 1993 the Monongahela Railway was merged into the Consolidated Rail Corporation (Conrail), which had previously bought out the shares of B&O successor CSX Transportation and Pittsburgh & Lake Erie.

In 2012, Norfolk Southern celebrated 30 years of being formed, and painted 20 locomotives in predecessor schemes to honor its heritage.