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
Saline River (Illinois) Saline River (Illinois) The Saline River is a tributary of the Ohio River, approximately long, in the Southern Illinois region of the U.S. state of Illinois. The river drains a large section of southeast Illinois, with a drainage basin of . The major tributaries include the South Fork, Middle Fork and North Fork, all lying within the Saline Valley. The once meandering swampy river was important among Native Americans and early settlers as a source of salt from numerous salt springs where it was commercially extracted in the early 19th century. From 1807 to 1818, Illinois paid the United States