Illinois

River running through Illinois, USA; length 440 km/273 mi. It is formed by the confluence of the Des Plaines and Kankakee rivers in northeast Illinois and drains an area of 72,520 sq km/28,000 sq mi into the Mississippi River.

Course After forming near Dresden, the river initially flows west to Ottawa, where it is joined by the Fox River. Turning southwest near Depue, it passes Peoria and joins the Mississippi 40 km/25 mi above St Louis, Missouri. The river's main tributaries are the Vermilion, Spoon, Sangamon, La Moine, Macoupin, and Mackinaw rivers.

History The first Europeans to explore the Illinois were the Frenchmen Louis Jolliet and Jacques Marquette, who travelled up the river in 1673. Principal occupants of the valley at that time were the Kaskakia, Sac, and Fox tribes. The area was heavily settled in the 1820s.