The Ohio River is the largest tributary, by volume, of the Mississippi River.This River is a naturally shallow river that was artificially deepened by a series of dams. The natural depth of the river varied from about 3 to 20 feet (0.91 to 6.1 m). The dams raise the water level and have turned the river largely into a series of reservoirs, eliminating shallow stretches and allowing for commercial navigation.
The Ohio River is formed by the confluence of the Allegheny and Monongahela rivers at Point State Park in Pittsburgh, Pennsylvania. From there, it flows northwest through Allegheny and Beaver counties, before making an abrupt turn to the south-southwest at the West Virginia–Ohio-Pennsylvania triple-state line (near East Liverpool, Ohio; Chester, West Virginia; and Midland, Pennsylvania).