U.S. Dept. of Agriculture. Miscellaneous publication

The Great Black Swamp (or Black Swamp) was a glacially fed wetland in northwest Ohio, northeast Indiana, and southeast Michigan that existed from the end of the Wisconsin glaciation until the late 19th century. Comprising extensive swamps and marshes interspersed with drier ground, it occupied what was formerly the southwestern part of proglacial Lake Maumee, a precursor to Lake Erie. It was the home of Indigenous nations for thousands of years until the Indian Removal Act in the 19th century. The Ohio Department of Natural Resources stated the Great Black Swamp covered 3,072,000 acres (1,243,000 ha) and its Lake Erie marshes covered 300,000 acres (120,000 ha). Other estimates claim the wetlands covered 1,500 square miles (3,900 km2); or 2,600 square miles (6,700 km2); or were 140 miles (230 km) wide.