The Ohio Country (sometimes called the Ohio Territory or Ohio Valley by the French) is the name used in the eighteenth century for the regions of North America west of the Appalachian Mountains and in the region of the upper Ohio River south of Lake Erie.

This area is disputed in the mid-eighteenth century by France and Great Britain.

The eponymous name is based on a 1740 act of the colonial Virginia legislature when the colony claims many of the trans-Allegheny territories and moneyed interests actively try to encourage settlement west of the Ohio River hoping to gain that Ohio River watershed with enabling legislation forming the Ohio Company.

One of the first frontier regions of the United States, the area encompasses roughly all of present-day Ohio, northwestern West Virginia, western Pennsylvania, and eastern Indiana.

These Virginia colonial property claims lead to the employment of many, including George Washington as a surveyor, his career as a militia officer and frictions with the French, various rival native Amerindian nations (the Iroquois, Miami, and Shawnee) and disputes with properties claims by other Colonies, which in part the act had been trying to minimize.

Virginia retains a claim to those territories into the American Revolutionary years, one less well publicized cause of which is the British Crown's attempt to hold in check emigration and settlement to the west of the Appalachians, while proof of its importance at the end of the colonial era is amply given in that the Virginia Colony formally declares war in 1774 on the region's Shawnee Nation, soon after winning Lord Dunmore's War gaining rights by treaty to settle the east bank Ohio Valley; results adverse to official British Crown policy.

After the Revolution and resolution of state claims to the territory, the Northwest Ordinance of 1787 establishes the boundaries of the Northwest Territory, which is larger than the Ohio Country.

The territory includes all the land of the United States west of Pennsylvania and northwest of the Ohio River.

It covers all of the modern states of Ohio, Indiana, Illinois, Michigan, Wisconsin, and the northeastern part of Minnesota. The area covers more than 260,000 square miles (670,000 square kilometers).