The Ohio River runs in a northwest direction out of Pennsylvania from Pittsburgh, and then southwest until it joins the Mississippi River in Illinois. The river is formed by Allegheny and Monongahela rivers. More water from it feeds the Mississippi River than any other body of water.
Illinois, Indiana, Kentucky, Ohio, Pennsylvania and West Virginia are all connected with the river. There are 20 dams that line the river and it provides drinking water for more than 3 million people.
The Ohio River also played an important part in history. The Meadowcroft Rockshelter is the oldest human residence known, dating back 16,000 years and located on one of the river´s tributaries.