# The New International Encyclopædia/Ohio River

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​ OHIO RIVER. The most important affluent of the Mississippi River in point of the amount of commerce, and the longest tributary excepting the Missouri (Map: United States, J 3). It is formed by the junction at Pittsburg of the Allegheny and Monongahela rivers, and is navigable, excepting at the lower stages of water, from Pittsburg to its confluence with the Mississippi, 975 miles. After leaving Pennsylvania it flows between Ohio, Indiana, and Illinois on the right, and West Virginia and Kentucky on the left. Its drainage basin is over 200,000 square miles, and the rainfall over the basin averages 43 inches a year. Its discharge of water averages 158,000 cubic feet a second, surpassing that of the Missouri by nearly 40,000 cubic feet. The elevation of the river above the sea is 1021 feet at Pittsburg and 322 feet at its mouth. Its mean rate of flow is 3 miles an hour, and its mean fall is about .70 of a foot to the mile. The Allegheny and Monongahela are regarded as having equal claims as the source of the river, though the Allegheny is longer, with 123 miles of navigation. The Allegheny rises on the plateau of northern Pennsylvania west of the Allegheny Mountains, drains Lake Chautauqua in New York, and descends through a series of narrow valleys to its junction with the Monongahela. The latter river (navigable for 60 miles) draws its farthest supplies from the rains and melting snows of the upland Allegheny valleys in the centre of West Virginia, and in the lower part of its course passes through a valley composed of Carboniferous rocks, where coal is mined almost at the water's edge. Below Pittsburg the Ohio winds through a wide flood plain between the inclosing hills, receiving waters from the north that rise ​only ten to twenty miles from the south shore of Lake Erie. The glacial drift in this north part of the Ohio basin changed the line of the water parting so that the crest of the divide between the Saint Lawrence and the Ohio basins is now ten or more miles nearer the lake than in the preglacial epoch. The chief northern tributary is the Wabash, a placid stream navigable by small boats to Terre Haute, Ind. Other northern affluents, as the Muskingum, the Scioto, and the Miami, descend, like the Allegheny, from the plain studded with lakes not far from Lake Erie. The southern affluents are larger, and rise, like the Monongahela, among the upland glades of the Appalachians or on the Appalachian plateau. The Kanawha (navigable to Charleston, W. Va.) and the Licking traverse salt-yielding regions. The Kentucky River (navigable to Beattyville, Ky.) joins the Ohio above the Louisville Rapids and marks the natural division between the middle and lower courses of the river. At Louisville a coral reef obstructs the Ohio with a series of rapids which disappear during the floods, but which arrested navigation at low water until the rapids were turned by lateral riverine canals. The greatest tributaries from the south are the Cumberland, navigable to Burnside, Ky., and the Tennessee, navigable to Knoxville.
Many fine towns and cities border the Ohio, the larger places standing chiefly at the mouths of the affluents. Below Louisville the valley broadens and the skirting hills retire to a great distance from the river banks. As the larger part of the drainage comes from the mountain districts, the Ohio is unable in times of very heavy rainfall or rapid thaw of the winter's snow to carry off the vast quantity of water suddenly emptied into it. The volume of its discharge has varied as much as eightfold. The difference between the high and low water marks is sometimes as much as 50 to 60 feet in a single season and in 1887 it exceeded 70 feet. The river at flood covers the lower parts of many towns on its banks, causing great loss of property and much suffering. On the other hand, in periods of drought the current is often reduced to a fordable depth above Cincinnati. These great variations in the level are a serious impediment to navigation. Boats loaded with many thousands of tons of coal and other freight destined for Ohio and Mississippi river points are frequently held up for weeks at Pittsburg waiting for enough water to float them. In spite of this drawback, the Ohio and its tributaries carry over 15,000,000 tons of freight a year, mainly coal, lumber, grain, and the product of iron and steel mills and the potteries on their banks. The total length of navigation on the river and its affluents is about 2300 miles. In the development of the West the Ohio played a prominent part.
Consult: Ellet, “Contributions to the Physical Geography of the United States,” in Smithsonian Institution Contributions to Knowledge (Washington, 1849); Bliss, “Dr. Saugrain's Relation of His Voyage Down the Ohio River,” in American Antiquarian Society Proceedings (Worcester, 1897).