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. 

The 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. 

It is named in Iroquoian or ,  "Good River" or and "Spelewathiipi". The river had great significance in the history of the Native Americans, as numerous civilizations formed along its valley. For thousands of years, Native Americans used the river as a major transportation and trading route. Its waters connected communities. In the five centuries before European conquest, the Mississippian culture built numerous regional chiefdoms and major earthwork mounds in the Ohio Valley, such as Angel Mounds near Evansville, Indiana, as well as in the Mississippi Valley and the Southeast. The Osage, Omaha, Ponca and Kaw lived in the Ohio Valley, but under pressure from the Iroquois to the northeast, migrated west of the Mississippi River to Missouri, Arkansas and Oklahoma in the 17th century.
How many state doe the Ohio River go through or by?
How many are included in it's drainage basin?
How many people use it for drinking water?
What is one of its tributaries?
Where does that rank in size among all its tributaries?
What river is the Ohio River a tributary of?
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Beginning where?
Where is that?
Where does it end up?
Is that that in Egypt?
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For what group is the river a big part of history?
What did they make along it?
What did it connect?
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What?
six
The river flows through or along the border of six states
15
and its drainage basin includes parts of 15 states
three million
It is the source of drinking water for three million people
Tennessee River
Through its largest tributary, the Tennessee River
The largest
Through its largest tributary, the Tennessee River
Mississippi
largest tributary, by volume, of the Mississippi River
cu ft/s
cu ft/s
westward
which streams westward from
Pittsburgh
westward from Pittsburgh, Pennsylvania
Pennsylvania
Pittsburgh, Pennsylvania
Cairo
 Cairo, Illinois
No
Cairo, Illinois
Illinois
Cairo, Illinois
Native Americans,
The river had great significance in the history of the Native Americans,
civilizations
 as numerous civilizations formed along its valley.
communities
Its waters connected communities
yes
Native Americans used the river as a major transportation and trading route
transportation
Native Americans used the river as a major transportation and trading route
yes
Native Americans used the river as a major transportation and trading route
trading
Native Americans used the river as a major transportation and trading route