The Illinois River is a river in the United States . It is in the state of Illinois . It is an important tributary of the Mississippi River . The length of the river is about 439 km.

Geography [ change | change source ]

The source of the river is in northeastern Illinois, near the city of Joliet . It flows west across Illinois, then southwest. It passes the city of Peoria , the largest city on the river.

It flows into southwestern Illinois. It joins the Mississippi River 40 km north of Saint Louis, Missouri . There is separate Illinois river that runs through the northernmost edge of Oklahoma.

The river was used for transportation by the Native Americans . It was also used by early French trappers. It was an important route between the Mississippi River and the Great Lakes .

In the 19th century a canal was built that connected the river to Lake Michigan . Large ships now use this canal to go from the Great Lakes to the Mississippi River. The canal goes through the city of Chicago . It is one of the reasons that Chicago became a big city.

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