| 1917 |
Cedar Rapids/Clear Lake Rabbits, Clinton Pilots, Dubuque Dubs/Charles City Tractorites, Fort Dodge Dodgers, La Crosse Infants, Marshalltown Ansons, Mason City Claydiggers, Waterloo Lions |
| 1916 |
Burlington Pathfinders/Ottumwa Packers, Cedar Rapids Rabbits, Clinton Pilots, Fort Dodge Dodgers, Marshalltown Ansons, Mason City Claydiggers, Muscatine Muskies, Waterloo Shamrocks |
| 1915 |
Burlington Pathfinders, Cedar Rapids Rabbits, Clinton Pilots, Keokuk Indians, Marshalltown Ansons, Mason City Claydiggers, Muscatine Muskies, Waterloo Jays |
| 1914 |
Burlington Pathfinders, Cedar Rapids Rabbits, Clinton Pilots, Keokuk Indians, Marshalltown Ansons, Muscatine Buttonmakers, Ottumwa Packers/Rock Island Islanders/Galesburg Pavers, Waterloo Jays |
| 1913 |
Burlington Pathfinders, Cedar Rapids Rabbits, Keokuk Indians, Kewanee Boilermakers, Monmouth Browns, Muscatine Wallopers, Ottumwa Packers, Waterloo Jays |
| 1912 |
Burlington Pathfinders, Galesburg Pavers, Hannibal Cannibals, Keokuk Indians, Kewanee Boilermakers, Monmouth Browns, Muscatine Wallopers, Ottumwa Speedboys |
| 1911 |
Burlington Pathfinders, Galesburg Pavers, Hannibal Cannibals, Keokuk Indians, Kewanee Boilermakers, Monmouth Browns, Muscatine Camels, Ottumwa Speedboys |
| 1910 |
Burlington Pathfinders, Galesburg Pavers, Hannibal Cannibals, Keokuk Indians, Kewanee Boilermakers, Monmouth Browns, Ottumwa Packers, Quincy Vets |
| 1909 |
Burlington Pathfinders, Hannibal Cannibals, Jacksonville Braves, Keokuk Indians, Kewanee Boilermakers, Ottumwa Packers, Quincy Vets, Waterloo Lulus |
| 1908 |
Burlington Pathfinders, Jacksonville Lunatics, Keokuk Indians, Kewanee Boilermakers, Oskaloosa Quakers, Ottumwa Packers, Quincy Gems, Waterloo Lulus |