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
Illinois River (Oregon) Illinois River (Oregon) The Illinois River is a tributary, about long, of the Rogue River in the U.S. state of Oregon. It drains part of the Klamath Mountains in northern California and southwestern Oregon. The river's main stem begins at the confluence of its east and west forks near Cave Junction in southern Josephine County. Its drainage basin includes Sucker Creek, which rises in the Red Buttes Wilderness, near Whiskey Peak on the California state line. The main stem flows generally northwest in a winding course past Kerby and through the Siskiyou National Forest and Kalmiopsis Wilderness. It joins the