Wabash, river, c.475 mi (765 km) long, rising in Grand Lake, W Ohio, and flowing NW into Ind., then generally SW through Ind., becoming the Ind.-Ill. border before emptying into the Ohio River; largest northern tributary of the Ohio. The Wabash's major tributaries are the Tippecanoe and White rivers. Dams on the Wabash control floods, produce hydroelectricity, and regulate navigation; sand and gravel barges constitute the chief traffic on the river. In the fertile Wabash basin corn and livestock are raised. Vincennes, Terre Haute, and Lafayette, Ind. are on the Wabash.

Wabash (wô´băsh´), city (1990 pop. 12,127), seat of Wabash co., N central Ind., on the Wabash River; inc. 1849. It is an agricultural trade center for wheat, corn, soybeans, vegetables, and fruit. There is diverse manufacturing. Wabash was the world's first electrically lighted city; one of the original street lamps is on exhibition in the county courthouse. Nearby Salamonie and Mississinewa dams (completed 1966 and 1967) provide flood protection and water recreation.