Southern Illinois Southern Illinois Southern Illinois (also known as "Little Egypt") is the southern third of the state of Illinois. The southern part of Illinois has a unique cultural and regional history. Part of downstate Illinois, the Southern Illinois region is bordered by the two most voluminous rivers in the United States: the Mississippi River and its connecting Missouri River to the west, and the Ohio River to the east and south with the Wabash as tributary. Southern Illinois' most populated city is Belleville at 44,478. Other principal cities include Alton, Centralia, Collinsville, Edwardsville, Effingham, O'Fallon, Harrisburg, Herrin, Mt. Vernon, Marion, and
Southern Illinois River-to-River Conference Conference. Southern Illinois River-to-River Conference The Southern Illinois River-to-River Conference (SIRR) is a high school athletic conference represented by 12 schools in southern Illinois. The conference is divided into two divisions. While technically in the same conference each division crowns its own champion, and each winner is regarded as the conference champion as if they were in two separate conferences. Schools are only required to play other schools within their own division although cross-divisional play is very common. Seven of the charter members of the River-to-River Conference were members of the old Southwest Egyptian Conference. Around 1991, the Southwest Egyptian