physical region in Alabama and Mississippi, U.S., so named for its soil. The Black Belt is a fertile plain, generally 25–30 miles (40–50 km) wide and stretching approximately 300 miles (480 km) across central Alabama and northeastern Mississippi. A region of dark, calcareous soils, it was one of the South's most important agricultural areas before the American Civil War. Though corn (maize) was also grown, cotton was the most important crop until the destructive effects of the boll weevil encouraged agricultural diversification in the early years of the 20th century. Beef cattle and soybeans are now also raised in the area.

Though strictly the name of a physical region, the term Black Belt has been borrowed by social scientists to denote those areas of the South where the plantation system, with its large number of black slaves, predominated before the Civil War.