Monongahela Valley League was an unlassified league based in Pennsylvania.
1893 Braddock, Duquesne, Homestead, Irwin, Wilkensburg, Wilmerding
1894 Braddock, Duquesne, Homestead, Wilkensburg
1905 Belle Vernon, Brownsville, Charleroi, Donora, Fayette City, Monongahela City
1906 to 1908 Not sure if this league played
1909 Belle Vernon, Brownsville, Donora, Fayette City, Monongahela City, Roscoe
1910 to 1938
1939 Belle Vernon, Charleroi, Donora Hilltops, Donora Zincs, Dunlevy, Fairhope, Monessen Association, Monessen Franks, Monongahela, New Eagle