The Black Swamp was a region in northwestern Ohio in the river valley of the Maumee River. The area was bounded by glacial moraine and had poor drainage. It was once covered by the glacial Lake Maumee. During the settlement period of the Old Northwest, the Black Swamp impeded westward and northwestward migration. German immigrants to the region began draining the swamp in the 1850s which made the land arable and prompted a settlement boom. The land thereafter was one of the most fertile in the state.