Southern Illinois took place in Williamson County between 1839 and 1876. This was unusual, as crime was almost non-existent in Illinois during its frontier years prior to this period of lawlessness. In 1858, Abraham Lincoln ran for the U.S. Senate against Stephen A. Douglas. A debate was held in seven towns in Illinois, one being near Jonesboro. Many of the people living in Southern Illinois were first- or second-generation Southerners. Cairo, Illinois, at the southern tip where the Ohio River joins the Mississippi, was of strategic importance. On either side of the rivers were states which, despite remaining in the Union, had
Southern Illinois River-to-River Conference approached by Benton, Herrin, Harrisburg, and West Frankfort for membership; these four schools were concerned over their small size relative to the other members of the South Seven Conference (where all four were then located) and sought out a conference more in line with their size. Massac County (then an independent school) was approached about becoming a member, and in 1993 the Southern Illinois River-to-River Conference was formed. At the start of the 2010-2011 school year Carterville left the Black Diamond Conference to join the Southern Illinois River-to-River Conference. Chester High School has taken their place in the Black Diamond