Southern Illinois the Ozarks of Missouri, is chiefly in southern Jackson, Union, northern Alexander and Johnson counties. The eastern area, more closely related to the Wabash Valley Seismic Zone, is mostly in northern Pope, southern Saline, Gallatin, eastern Johnson and southern Williamson counties. The Shawnee National Forest covers a large territory, including seven wilderness areas: Garden of the Gods, Bay Creek, Clear Springs, Bald Knob, Burden Falls, Lusk Creek, and Panthers Den. Of southern Illinois' rivers, only the Mississippi and the Ohio are navigable for modern commerce. The Big Muddy River, Marys River, Saline River and Cache River run their courses in
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