Iron & Oil League was a non classified league in 1885 and 1892. The league was Class C in 1895 and Class D in 1898.
1885 unknown teams
1892 unknown teams
1895 Franklin PA, New Castle PA, Oil City PA, Sharon PA, Titusville Pa
1898 Bradford PA, Celeron NY, Meadville PA, Oil City PA, Olean NY and Warren, PA. During the season, the Oil City franchise moved to Dunkirk-Fredonia NY.