county, central South Carolina, U.S. It is bordered to the west by the Wateree River, which flows into the Congaree River; the narrow far eastern border is the Lynches River. The county is also drained by the Black and Pocotaligo rivers. Shaw Air Force Base, Manchester State Forest, Poinsett State Park, and Woods Bay State Park (in a Carolina bay, or isolated swampy area) are all located there. Sumter county is an agricultural region situated both on low Fall Line hills and on a flat, often swampy area of the inner Coastal Plain.