The Tri-County Conference was a league that ran from 1950 to 1965, and is considered a direct forerunner to the Mid-Indiana Conference. The league began in 1950 as the Howard-Miami Conference, as the three schools left from the post-consolidation Howard County Conference joined with three schools from Miami County. The conference changed its name to the TCC when Swayzee and Sweetser, from Grant County joined. When school consolidation forced the conference to look outside its footprint to find similar-sized schools, in 1965 it became the current MIC.
This should not be confused with conferences of the same name based in the southern and western portions of the state.
| School | Location | Mascot | Colors |
| Year joined | Previous conference | Year left | Conference joined | |
|---|---|---|---|---|---|---|---|---|---|
| Bunker Hill | Bunker Hill | Minutemen | 52 Miami | 1950 | Miami County | 1963 | none (consolidated into Maconaquah) | ||
| Clay Township | Loree | Indians | 52 Miami | 1950 | Miami County | 1963 | none (consolidated into Maconaquah) | ||
| Converse | Converse | Bordermen | 52 Miami | 1950 | Miami County | 1957 | none (consolidated into Oak Hill) | ||
| Eastern (Greentown) | Greentown | Comets | 34 Howard | 1950 | new school | 1965 | Mid-Indiana | ||
| Northwestern | Kokomo | Tigers | 34 Howard | 1950 | Howard County | 1965 | Mid-Indiana | ||
| Western | Russiaville | Panthers | 34 Howard | 1950 | Howard County | 1958 | Hoosier | ||
| Swayzee | Swayzee | Speed Kings | 27 Grant | 1955 | Grant County | 1957 | none (consolidated into Oak Hill) | ||
| Sweetser | Sweetser | Braves | 27 Grant | 1955 | Grant County | 1965 | none (consolidated into Oak Hill) | ||
| Oak Hill | Converse | Golden Eagles | 27 Grant | 1957 | none (new school) | 1965 | Mid-Indiana | ||
| Maconaquah | Bunker Hill | Braves | 52 Miami | 1963 | none (new school) | 1965 | Mid-Indiana |