The Des Plaines River has great historic significance for the Chicago, Illinois, area. The river merges its flow with the Kankakee southwest of Joliet to create the Illinois River, a significant tributary of the Mississippi. In 1673, when Marquette and Joliet made their historic voyage of discovery, Native American Indians showed them a preferred route from the Mississippi Valley to the Great Lakes. That route went up the Illinois River and continued along the Des Plaines to the Chicago Portage. The Des Plaines has been traveled by native people for untold generations, and has become the principal water route westward from Lake Michigan toward the Mississippi River.