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
Muddy Run (West Branch Susquehanna River tributary) Muddy Run (West Branch Susquehanna River tributary) Muddy Run is a tributary of the West Branch Susquehanna River in Northumberland County, Pennsylvania, in the United States. It is in length. The creek is several miles northeast of the community of Milton. Main land uses include agricultural land and forest. The area of the creek's watershed is 11.4 square miles, most of which is agricultural land. Muddy Run is entirely within Turbot Township. Most of the rock in the watershed is shale. The most common soil series is the Berks-Weikert-Bedington series. Muddy Run begins in a valley in eastern Turbot Township,