ILLINOIS RIVER

navigable stream formed by the junction of the Des Plaines and Kankakee rivers in Grundy county, northeastern Illinois, U.S. It flows generally west across the state until it reaches Hennepin, where it turns abruptly south to join the Mississippi River at Grafton after a course of 273 miles (440 km). The Illinois drains an area of approximately 25,000 square miles (64,750 square km) and occasionally broadens into wide expanses such as Peoria Lake. The Illinois and Michigan Canal, constructed from the Chicago River to the Illinois River (1848) at a point near La Salle, made navigation between these streams possible, and when the Illinois Waterway was completed in 1933, shipping between the Great Lakes and the Gulf of Mexico via the waterway and the Mississippi River became practicable. Cities that are situated along the river's course include Morris, Ottawa, La Salle, Peru, Peoria, Pekin, Havanna, and Beardstown. Its tributaries include the Spoon and Sangamon rivers and the Fox, Vermilion, Mackinaw, and La Moine rivers. State parks along the Illinois River include Starved Rock (near Ottawa), Fort Creve Coeur (near Peoria), and Pere Marquette (near the confluence with the Mississippi River).