River, northeastern Illinois, U.S. A small river, consisting of a northern and southern branch, it originally flowed through Chicago into Lake Michigan .
After a severe storm in 1885 caused the river to empty large amounts of polluted water into the lake, its flow was reversed by constructing a canal in 1900, the building of which was considered a significant engineering feat. Now flowing inland, it is connected with the Des Plaines River by the Chicago Sanitary and Ship Canal.