The Black River is a 151-mile-long (243 km) blackwater river in South Carolina in the United States. It courses through Sumter, Clarendon, and Williamsburg counties before merging with the Great Pee Dee River in Georgetown County. The river was called the Wee Nee by the Native Americans who once inhabited the area. In June 2001, a 75-mile segment of the river was designated a State Scenic River.