Former Conferences
- Cook County High School League (1889–1913)
- Four Rivers Conference
- Illini Central Conference
- Little 7 Conference (1921–1995)
- Mid-State Conference
- New Salem Conference
- North Egypt Conference (1938-2003)
- Olympic Conference (1976-2010)
- SICA — (South Inter-Conference Association, dissolved 2006)
- Southwest Egyptian Conference (????-1993)
- Suburban League (1913–1975)
- Suburban Prairie Conference (1995-2005)
- Tollway Athletic Conference
- West Prairie Trail Conference
- Western Sun Conference
Read more about this topic: List Of Illinois High School Association Member Conferences