The Ohio Valley is the valley formed by the Ohio River and its tributaries and includes major portions of Indiana, Ohio, Kentucky and West Virginia, southeastern portions of Illinois, western portions of Pennsylvania, north central portions of Tennessee and small portions of Michigan, New York, Virginia and North Carolina. Map B shows the Ohio and its tributaries superimposed on modern state boundaries. The Ohio River flows west from the Appalachians providing the boundaries among Kentucky (south of the River) and West Virginia (southeast of the River) and Ohio and Indiana (north of the River) and Illinois (northwest of the River). The River begins in Pittsburgh, Pennsylvania, where the Allegheny and the Monongahela Rivers flow together and ends at Cairo, Illinois, where it flows into the Mississippi River which in turn flows south to the Gulf of Mexico. The Ohio River is 981 miles long. The entire area, or basin, is about 200,000 square miles or approximately the size of France.

This map is from the Ohio River Forcast Center (OHFRC) of the National Weather Center.

The Ohio Valley was well suited for hunting and agriculture, and its control was long contested by Native American Nations, France, England, the colonies and eventually the United States. French claims ended with French expulsion from Canada in the war that the colonists called the French and Indian War. The United States gained nominal control of the area from England with the end of the Revolutionary War, but Native American Nations, fitfully supported by Britain, continued to deny U.S. claims and to contest U.S. possession. The War of 1812 settled the matter as effective opposition to U.S. claims ended.

Today, 25 million people live in this area. Nonetheless, it is difficult for us to envision the Ohio Valley as a whole because it was divided by significant political and cultural boundaries almost from the beginning of U.S. control with slavery allowed south of the Ohio and slavery banned north of the Ohio in the Northwest Territory. Further confusing the matter, the name was appropriated by Ohio, the first state formed north of the river.