Beginning in the late 1970s, frequent membership changes happened because the league consisted of some of the smallest schools in the state.
The conference had 6 teams, but four members left in 2014, and another explored options for whole grade sharing that would end its independent sports program.
The eight original members of the conference were Ruthven, Titonka, Swea City, Sioux Rapids, Marathon, West Bend, Terril, and Graettinger.
In 1958, Titonka, Armstrong, Swea City, and Thompson left the league, to help form the State Line Conference.
Sioux Valley was created in 1959 from the consolidation of Peterson and Linn Grove, along with tiny rural districts Brooke, Cornell, and Highview, to become the eighth member of the Cornbelt Conference.
Due to Marathon's departure in 1977 to join with Laurens, this left the league at 14 schools: the eight existing league schools, as well as Ayrshire, South Clay, Clay Central, Ocheyedan, Harris-Lake Park, and Arnolds Park.
In 1984, the Ayrshire district began sending students elsewhere, then joined Ruthven to form Ruthven-Ayrshire Community School.
The State Line Conference disbanded, leaving the Cornbelt to pickup league members Lincoln Central of Gruver, Armstrong-Ringsted, Sentral-Burt of Fenton, and North Kossuth of Swea City.
Harris-Lake Park joined the War Eagle Conference, along with independent Trinity Christian of Hull; the next year, Clay Central-Everly followed suit.