The Ohio River is a major river in the United States that runs from Pittsburgh, Pennsylvania to Cairo, Illinois. It is 981 miles long and is the largest tributary of the Mississippi River. The three crossword solutions for the term Ohio River are Miami (5 letters), Scioto (6 letters), and Maumee (6 letters). Miami is a tributary of the Ohio River located in western Ohio. Scioto is a river in central and southern Ohio that flows into the Ohio River. Maumee is a river in northwestern Ohio that also flows into the Ohio River.