The Capitol Conference was a high schoolathletic conference in the Illinois High School Association, based in Central Illinois. The conference operated from 1964 to 1983. The original membership roster included Decatur Eisenhower, Decatur MacArthur, Jacksonville, Springfield Griffin, and Springfield Lanphier. Springfield Southeast was admitted in 1967, Champaign Centennial in 1968, and Normal Community in 1971. The conference remained at eight members for the remainder of its history. The impetus for its demise came inadvertently and unknowingly from a member of the neighboring Big Twelve Conference. At the time, the Big Twelve Conference membership roster included Bloomington, Champaign Central, Danville, Stephen Decatur, Lincoln, Mattoon, Springfield, and Urbana. Initial discussions were instigated by representatives of Springfield High School to look into the potential feasibility of swapping schools within the two conferences where there was some common city "overlap". This would allow each conference to align even more tightly geographically, thus increasing rivalries and reducing costs. Rather than proceed in that direction, the remaining members of the Big Twelve Conference alternatively decided to offer membership to all of the Capitol Conference non-Springfield "overlap" institutions plus Rantoul, while jettisoning Springfield. Those schools accepted, leaving the Capitol Conference with only Jacksonville, Springfield Griffin, Springfield Lanphier, and Springfield Southeast. As a result, the conference folded. Jacksonville and Springfield Griffin remained independent, while Springfield Lanphier and Springfield Southeast joined the Peoria-based Mid-State # Conference. In 1993, the four former Capitol Conference outliers came back together in the newly formed Central State Eight Conference. Its original roster also included original Big Twelve Conference castoff Springfield as well as current Big Twelve Conference member Lincoln. Chatham Glenwood and Taylorville rounded out the initial eight. Former Capitol Conference schools Decatur Eisenhower and Decatur MacArthur subsequently joined the Central State Eight Conference in 2014.
