The Wabash River (French: Ouabache) is a 503-mile-long (810 km) river in Ohio and Indiana, United States, that flows from the headwaters near the middle of Ohio's western border northwest then southwest across northern Indiana turning south along the Illinois border where the southern portion forms the Indiana-Illinois border before flowing into the Ohio River. It is the largest northern tributary of the Ohio River. From the dam near Huntington, Indiana, to its terminus at the Ohio River, the Wabash flows freely for 411 miles (661 km). Its watershed drains most of Indiana. The Tippecanoe River, White River, Embarras River ... Source: Wikipedia