Name / Description

Ohio River





Length (miles)


Additional Notes

981 miles long; formed by the confluence of the Allegheny and Monongahela rivers in SW Pa., in downtown Pittsburgh (40�26'N 80�00'W); 1st flows NW to Monaca, where it receives Beaver R. from N, then generally SW, forms Ohio-W.Va. state line and flows past Steubenville, Ohio, Wheeling and Huntington, W.Va., continuing WNW forming Ohio-Ky. state line, past Ashland, Ky., and Portsmouth and Cincinatti, Ohio, turns WSW, forms Ind.-Ky. and Ill.-Ky. state line, flowing past Louisville and Owensboro, Ky., Evansville, Ind., and Paducah, Ky., entering Mississippi R. at Cairo, Ill., opposite Mo. Receives Kentucky R. from S, 40 mi/64 km NE of Louisville; receives Wabash R. from N, 28 mi/45 km WSW of Evansville; receives Cumberland R. and Kentucky R. 12 miles ENE and 3 miles ESE of Paducah, respectively. The Ohio is navigable for its entire length; a series of locks and dams improves its navigability and controls flooding. The Ohio's course follows a portion of the S edge of the region covered by continental ice during the late Cenozoic era; glacial meltwater probably cut its original channel. The river is a major tributary of the Mississippi and supplies more water to it than does the Missouri R. The Ohio R. basin covers c.204,000 sq miles; the chief tributaries are the Tennessee, Cumberland, Wabash, and Kentucky. The Ohio is prone to spring flooding, and extensive flood-control and protection devices have been constructed along the river and its tributaries. These devices also improve the river's navigability; a 9-ft channel is maintained along its entire length. A system of modern locks and dams, constructed since 1955 to replace older structures, speeds the transit of barges and leisure craft. A canal (1st opened in 1830) at Louisville bypasses the Falls of the Ohio, a 2.25-mile-long series of rapids having a 24 ft drop. Oil and steel account for most of the cargoes moved on the river. The principal river ports are Cincinnati, Louisville, and Pittsburgh. The Ohio R. basin is one of the most populated and industrialized regions of the U.S. Eight states (Ill., Ind., Ky., N.Y., Ohio, Pa., Va., and W.Va.) affected by the river's industrial pollution ratified (1948) the Ohio R. Valley Sanitation Compact. Some results of their cleanup efforts have become discernible, and the river now supports marinas and recreational facilities. The Fr. explorer La Salle reportedly reached the Ohio R. in 1669, but there was no significant interest in the valley until the French and the British began to struggle for control of the river in the 1750s. An early settlement was established at the forks of the Ohio (modern Pittsburgh) by the Ohio Co. of Virginia in 1749, but it was captured by the French in 1754, and the unfinished Fort Prince George was renamed Fort Duquesne; it was recaptured by the British and renamed Fort Pitt in 1758. At the end of the Fr. and Indian Wars, Britain gained control of the river by the treaty of 1763, but settlement of the area was prohibited. Britain ceded the region to the U.S. at the end of the Revolutionary War (1783), and it was opened to settlement by the Ordinance of 1787, which established the Northwest Territory. Until the opening of the Erie Canal in 1825, the Ohio R. was the main route to the newly opened West and the principal means of market transportation of the region's growing farm output. Traffic declined on the river after the RR was built in the mid-1800s, although it revived after World War II. The Ohio R. remains a vital link in the river transportation system of the Midwest. Most shipping is done with barges pushed by towboats.