Ohio State League was an independent league - 1884, 1886-87, 1889, 1893, 1897, 1899, 1935 and Class D - 1908-1916, 1936-1941, 1944-1951 and Class F - 1898.
1884 Chillicothe OH, Dayton OH, Hamilton OH, Ironton OH, Portsmouth OH, Springfield OH
1885 Not sure if this league played
1886 Cincinnati OH, Columbus OH, Richmond IN, Washington Court House OH
1887 Akron OH, Columbus OH, Kalamazoo MI, Mansfield OH, Sandusky OH, Steubenville OH, Wheeling WV, Zanesville OH, Canton OH
1888 Not sure if this league played
1889 Akron Oh, Newark OH, Tiffin OH, Youngstown OH
1890 to 1982 Not sure if this league played
1893 Akron OH, Canton OH, Mansfield OH, Sandusky OH, Springfield OH
1894 to 1896 Not sure if this league played
1897 Akron OH, Canton OH, Chillicothe OH, Cincinnati OH, Dover OH, New Philadelphia OH
1898 Canton OH, Coshocton OH, Massillion OH, Salem OH, Wheeling WV, Zanesville OH
1899 Cambridge OH, Ravenna OH and Uhrichsville OH entered the league; Salem left the league.
1900 to 1908 Not sure if this league played
1908 Lancaster OH, Lima OH, Mansfield OH, Marion OH, Newark OH, Springfield Oh. During the season, Springfield team moved to Portsmoth OH.
1909 No team entered or left the league.
1910 Chillicothe, OH entered the league; Mansfield left the league.
1911 Hamilton, OH and Springfield, OH entered the league. During the season, Newark franchise played some home games in Piqua, OH.
1912 Mansfield, Hamilton, Lancaster and Springfield left the league. During the season the Marion franchise move to Ironton, OH.
1913 Charleston WV, Hamilton OH, Hungtington WV, Lexington, Ky and Maysville, Ky entered the league; Lima, Mansfield and Newark left the league.
1914 Newport, Ky entered the league; Hamilton left the league. During the season , Newport franchise moved to Paris, KY.
1915 Frankfort, KY entered the league; Huntington, Maysville and Paris left the league. During the season, Chillicothe moved to Huntington, WV and then to Maysville, Oh.
1916 Huntington, WV entered the league; Ironton left the league. During the season, Charleston franchise moved to Chillicothe, OH.
1935 Alliance OH, Canton OH, Cleveland OH, Mansfield OH, New Philadelphia OH, Tiffin OH
1936 Fostoria OH, Fremont OH and Sandusky, OH entered the league; Alliance, Canton and Cleveland left the league.
1937 Findlay, Oh entered the league; New Philadelphia left the league. During the season, Sandusky franchise moved to Marion OH.
1938 Mansfield and Marion left the league.
1939 Lima, OH and Mansfield, OH entered the league.
1940 No teams entered or left the league.
1941 No teams entered or left the league.
1944 Lima OH, Marion OH, Middletown OH, Newark OH, Springfield OH, Zanesville OH
1945 No teams entered or left the league
1946 Dayton OH and Richmond, IN In entered the league.
1947 Muncie, IN entered the league; Middletown left the league.
1948 See Ohio-Indiana League from 1948 to 1951.