Des Plaines (dĕs plānz), city (1990 pop. 53,223), Cook co., NE Ill., a suburb of Chicago on the Des Plaines River; inc. 1925. Among its manufactures are chemicals and electronic equipment. It was founded in the 1830s as the town of Rand; the name was changed in 1869, and Riverview was annexed in 1925. O'Hare International Airport is to the south.

Des Plaines, river, 110 mi (177 km) long, rising in SE Wis., and flowing S and SW through NE Ill., joining the Kankakee River S of Joliet, Ill., to form the Illinois River. The lower Des Plaines is part of the Illinois Waterway.