Ohio is a Midwestern state in the Great Lakes region of the United States. The state takes its name from the Ohio River, whose name in turn originated from the Seneca word ohiːyo', meaning "good river", "great river" or "large creek". The Ohio River forms its southern border, though nearly all of the river itself belongs to Kentucky and West Virginia.
Significant rivers within the state include the Cuyahoga River, Great Miami River, Maumee River, Muskingum River, and Scioto River. The rivers in the northern part of the state drain into the northern Atlantic Ocean via Lake Erie and the St. Lawrence River, and the rivers in the southern part of the state drain into the Gulf of Mexico via the Ohio River and then the Mississippi.
The worst weather disaster in Ohio history occurred along the Great Miami River in 1913. Known as the Great Dayton Flood, the entire Miami River watershed flooded, including the downtown business district of Dayton. As a result, the Miami Conservancy District was created as the first major flood plain engineering project in Ohio and the United States.