<Tr> <Td> - max </Td> <Td> 1,850,000 cu ft / s (52,386 m / s) </Td> </Tr> <Tr> <Td_colspan="2"> Ohio River basin </Td> </Tr> <P> The Ohio River, which streams westward from Pittsburgh, Pennsylvania, to Cairo, Illinois, is the largest tributary, by volume, of the Mississippi River in the United States . At the confluence, the Ohio is considerably bigger than the Mississippi (Ohio at Cairo: 281,500 cu ft / s (7,960 m / s); Mississippi at Thebes: 208,200 cu ft / s (5,897 m / s)) and, thus, is hydrologically the main stream of the whole river system . </P> <P> The 981 - mile (1,579 km) river flows through or along the border of six states, and its drainage basin includes parts of 15 states . Through its largest tributary, the Tennessee River, the basin includes many of the states of the southeastern U.S. It is the source of drinking water for three million people . </P>

Where is the ohio river valley on a map
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