Ohio ( /oʊˈhaɪ.oʊ/ (help·info)) is a Midwestern state of the United States. The thirty-fourth largest state by area in the U.S., it is the seventh-most populous with nearly 11.5 million residents. Ohio, whose name was derived from the Seneca word ohi:yo’, meaning "large creek," was formed primarily from the Ohio Territory and was admitted to the Union as the seventeenth state (and the first under the Northwest Ordinance) on March 1, 1803. Ohio is known as the "Buckeye State" for its prevalence of Ohio Buckeye trees, and, as such, Ohioans are also known as "Buckeyes."

The government of Ohio is composed of the executive branch, led by the Governor; the legislative branch, which comprises the Ohio General Assembly; and the judicial branch, which is led by the Supreme Court. Currently, Ohio occupies 18 seats in the United States House of Representatives. Ohio is known for its status as both a swing state and a bellwether in national elections.

The population density of Ohio ranks ninth among all U.S. states. Nonetheless, Ohio currently suffers from a negative net population migration, and an increasing rate of unemployment.