Kaskaskia River

The Kaskaskia River is a tributary of the Mississippi River, approximately 325 miles (523 km) long, in central and southern Illinois in the United States. The second largest river system within Illinois, it drains a rural area of farms, as well as rolling hills along river bottoms of hardwood forests in its lower reaches. The lower reaches of the river have been canalized to allow barge traffic.

"Cascasquia" is an alternative, supposedly more French, spelling of "Kaskaskia" that is sometimes encountered. It was named after a clan of the Illiniwek encountered by the early French Jesuits and other settlers. "Okaw River" was an alternative name for the Kaskaskia that persists in place names along the river, including Okawville, and in a major tributary, the West Okaw River.