Chesterfield County is a county located in the U.S. state of South Carolina. As of the 2010 census, its population was 46,734. Its county seat is Chesterfield. The county was formed in 1785, but was part of the Cheraws District until 1800, at which time Chesterfield became a district. Under the 1867 state constitution passed during the Reconstruction era, South Carolina districts became counties with home rule.