| 1961 | B | Burlington Bees, Cedar Rapids Braves, Des Moines Demons, Fox Cities Foxes, Lincoln Chiefs, Topeka Reds |
| 1960 | B | Burlington Bees, Cedar Rapids Braves, Des Moines Demons, Fox Cities Foxes, Green Bay Dodgers, Lincoln Chiefs, Sioux City Soos, Topeka Reds |
| 1959 | B | Burlington Bees, Cedar Rapids Braves, Des Moines Demons, Fox Cities Foxes, Green Bay Bluejays, Lincoln Chiefs, Sioux City Soos, Topeka Hawks |
| 1958 | B | Burlington Bees, Cedar Rapids Braves, Davenport DavSox, Fox Cities Foxes, Green Bay Bluejays, Rochester/Winona A's |
| 1957 | B | Burlington Bees, Cedar Rapids Raiders, Davenport DavSox, Evansville Braves, Keokuk Kernels, Peoria Chiefs |
| 1956 | B | Burlington Bees, Cedar Rapids Raiders, Evansville Braves, Keokuk Kernels, Peoria Chiefs, Quincy Gems, Terre Haute Tigers, Waterloo White Hawks |
| 1955 | B | Burlington Bees, Cedar Rapids Raiders, Evansville Braves, Keokuk Kernels, Peoria Chiefs, Quincy Gems, Terre Haute Tigers, Waterloo White Hawks |
| 1954 | B | Burlington Bees, Cedar Rapids Indians, Evansville Braves, Keokuk Kernels, Peoria Chiefs, Quincy Gems, Terre Haute Phillies, Waterloo White Hawks |
| 1953 | B | Burlington Flints, Cedar Rapids Indians, Evansville Braves, Keokuk Kernels, Peoria Chiefs, Quincy Gems, Terre Haute Phillies, Waterloo White Hawks |
| 1952 | B | Burlington Flints, Cedar Rapids Indians, Davenport Tigers, Evansville Braves, Keokuk Kernels, Quincy Gems, Terre Haute Phillies, Waterloo White Hawks |
| 1951 | B | Cedar Rapids Indians, Davenport Tigers, Evansville Braves, Quincy Gems, Terre Haute Phillies, Waterloo White Hawks |
| 1950 | B | Cedar Rapids Indians, Danville Dodgers, Davenport Quads, Decatur Commodores, Evansville Braves, Quincy Gems, Terre Haute Phillies, Waterloo White Hawks |
| 1949 | B | Danville Dodgers, Davenport Pirates, Decatur Cubs, Evansville Braves, Quincy Gems, Springfield Browns, Terre Haute Phillies, Waterloo White Hawks |
| 1948 | B | Danville Dodgers, Davenport Pirates, Decatur Commodores, Evansville Braves, Quincy Gems, Springfield Browns, Terre Haute Phillies, Waterloo White Hawks |
| 1947 | B | Danville Dodgers, Davenport Cubs, Decatur Commodores, Evansville Braves, Quincy Gems, Springfield Browns, Terre Haute Phillies, Waterloo White Hawks |
| 1946 | B | Danville Dodgers, Davenport Cubs, Decatur Commodores, Evansville Braves, Quincy Gems, Springfield Browns, Terre Haute Phillies, Waterloo White Hawks |
| 1942 | B | Cedar Rapids Raiders, Decatur Commodores, Evansville Bees, Madison Blues, Springfield Browns, Waterloo Hawks |
| 1941 | B | Cedar Rapids Raiders, Clinton Giants, Decatur Commodores, Evansville Bees, Madison Blues, Moline Plow Boys, Springfield Browns, Waterloo Hawks |
| 1940 | B | Cedar Rapids Raiders, Clinton Giants, Decatur Commodores, Evansville Bees, Madison Blues, Moline Plow Boys, Springfield Browns, Waterloo Hawks |
| 1939 | B | Bloomington Bloomers, Cedar Rapids Raiders, Clinton Giants, Decatur Commodores, Evansville Bees, Moline Plow Boys, Springfield Browns, Waterloo Red Hawks |
| 1938 | B | Bloomington Bloomers, Cedar Rapids Raiders, Clinton Owls, Decatur Commodores, Evansville Bees, Moline Plow Boys, Springfield Browns, Waterloo Red Hawks |
| 1937 | B | Bloomington Bengals, Clinton Owls, Decatur Commodores, Moline Plow Boys, Peoria Reds, Terre Haute Tots |
| 1935 | B | Bloomington Bloomers, Decatur Commodores, Fort Wayne Chiefs, Peoria Tractors, Springfield Senators, Terre Haute Tots |
| 1932 | B | Danville Veterans, Decatur Commodores, Peoria Tractors, Quincy Indians, Springfield Senators, Terre Haute Tots |
| 1931 | B | Bloomington Cubs, Danville Veterans, Decatur Commodores, Evansville Hubs, Peoria Tractors, Quincy Indians, Springfield Senators, Terre Haute Tots |
| 1930 | B | Bloomington Cubs, Danville Veterans, Decatur Commodores, Evansville Hubs, Peoria Tractors, Quincy Indians, Springfield Senators, Terre Haute Tots |
| 1929 | B | Bloomington Bloomers, Danville Veterans, Decatur Commodores, Evansville Hubs, Peoria Tractors, Quincy Indians, Springfield Senators, Terre Haute Tots |
| 1928 | B | Bloomington Bloomers, Danville Veterans, Decatur Commodores, Evansville Hubs, Peoria Tractors, Quincy Indians, Springfield Senators, Terre Haute Tots |
| 1927 | B | Bloomington Bloomers, Danville Veterans, Decatur Commodores, Evansville Hubs, Peoria Tractors, Quincy Red Birds, Springfield Senators, Terre Haute Tots |
| 1926 | B | Bloomington Bloomers, Danville Veterans, Decatur Commodores, Evansville Hubs, Peoria Tractors, Quincy Red Birds, Springfield Senators, Terre Haute Tots |
| 1925 | B | Bloomington Bloomers, Danville Veterans, Decatur Commodores, Evansville Pocketeers, Peoria Tractors, Quincy Red Birds, Springfield Senators, Terre Haute Tots |
| 1924 | B | Bloomington Bloomers, Danville Veterans, Decatur Commodores, Evansville Little Evas, Peoria Tractors, Terre Haute Tots |
| 1923 | B | Bloomington Bloomers, Danville Veterans, Decatur Commodores, Evansville Evas, Moline Plowboys, Peoria Tractors, Rockford Rox, Terre Haute Tots |
| 1922 | B | Bloomington Bloomers, Danville Veterans, Decatur Commodores, Evansville Evas, Moline Plowboys, Peoria Tractors, Rockford Rox, Terre Haute Tots |
| 1921 | B | Bloomington Bloomers, Cedar Rapids Rabbits, Evansville Evas, Moline Plowboys, Peoria Tractors, Rock Island Islanders, Rockford Rox, Terre Haute Tots |
| 1920 | B | Bloomington Bloomers, Cedar Rapids Rabbits, Evansville Evas, Moline Plowboys, Peoria Tractors, Rock Island Islanders, Rockford Rox, Terre Haute Browns |
| 1919 | B | Bloomington Bloomers, Evansville Evas, Moline Plowboys, Peoria Tractors, Rockford Rox, Terre Haute Browns |
| 1917 | B | Alton Blues, Bloomington Bloomers, Hannibal Mules, Moline Plowboys, Peoria Distillers, Quincy Gems, Rock Island Islanders, Rockford Rox |
| 1916 | B | Bloomington Bloomers, Davenport Blue Sox, Hannibal Mules, Moline Plowboys, Peoria Distillers, Quincy Gems, Rock Island Islanders, Rockford Wakes |
| 1915 | B | Bloomington Bloomers, Davenport Blue Sox, Decatur Commodores, Dubuque Dubs/Freeport Commons, Moline Plowboys, Peoria Distillers, Quincy Gems, Rockford Wakes |
| 1914 | B | Bloomington Bloomers, Danville Speakers/Moline Plowboys, Davenport Blue Sox, Decatur Commodores, Dubuque Dubs, Peoria Distillers, Quincy Gems, Springfield Watchmakers |
| 1913 | B | Bloomington Bloomers, Danville Speakers, Davenport Blue Sox, Decatur Commodores, Dubuque Dubs, Peoria Distillers, Quincy Gems, Springfield Watchmakers |
| 1912 | B | Bloomington Bloomers, Danville Speakers, Davenport Prodigals, Decatur Commodores, Dubuque Dubs, Peoria Distillers, Quincy Old Soldiers, Springfield Senators |
| 1911 | B | Danville Speakers, Davenport Prodigals, Dubuque Hustlers, Peoria Distillers, Quincy Infants, Rock Island Islanders, Springfield Senators/Decatur Nomads, Waterloo Boosters |
| 1910 | B | Bloomington Bloomers, Danville Speakers, Davenport Prodigals, Dubuque Dubs, Peoria Distillers, Rock Island Islanders, Springfield Senators, Waterloo Boosters |
| 1909 | B | Bloomington Bloomers, Cedar Rapids Rabbits, Davenport Prodigals, Decatur Commodores, Dubuque Dubs, Peoria Distillers, Rock Island Islanders, Springfield Senators |
| 1908 | B | Bloomington Bloomers, Cedar Rapids Rabbits, Clinton Infants, Decatur Commodores, Dubuque Dubs, Peoria Distillers, Rock Island Islanders, Springfield Senators |
| 1907 | B | Bloomington Bloomers, Cedar Rapids Rabbits, Clinton Infants, Decatur Commodores, Dubuque Dubs, Peoria Distillers, Rock Island Islanders, Springfield Senators |
| 1906 | B | Bloomington Bloomers, Cedar Rapids Rabbits, Davenport Knickerbockers, Decatur Commodores, Dubuque Dubs, Peoria Distillers, Rock Island Islanders, Springfield Senators |
| 1905 | B | Bloomington Bloomers, Cedar Rapids Rabbits, Davenport Riversides, Decatur Commodores, Dubuque Shamrocks, Peoria Distillers, Rock Island Islanders, Springfield Senators |
| 1904 | B | Bloomington Bloomers, Cedar Rapids Rabbits, Davenport River Rats, Decatur Commodores, Dubuque Shamrocks, Rock Island Islanders, Rockford Red Sox, Springfield Hustlers |
| 1903 | B | Bloomington Bloomers, Cedar Rapids Rabbits, Davenport River Rats, Decatur Commodores, Dubuque Shamrocks, Joliet Standards/Springfield Foot Trackers, Rock Island Islanders, Rockford Red Sox |
| 1902 | B | Bloomington Blues, Cedar Rapids Rabbits, Davenport River Rats, Decatur Commodores, Evansville River Rats, Rock Island Islanders, Rockford Red Sox, Terre Haute Hottentots |
| 1901 | D | Bloomington Blues, Cedar Rapids Rabbitts, Davenport River Rats, Decatur Commodores, Evansville River Rats, Rock Island Islanders, Rockford Red Sox, Terre Haute Hottentots |
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