McCormick County is a county located in the U.S. state of South Carolina. As of the 2020 census, its population was 9,526, making it the second-least populous county in South Carolina. Its county seat is McCormick. The county was formed in 1916 from parts of Edgefield, Abbeville, and Greenwood counties.

Edgefield County is a county located on the western border of the U.S. state of South Carolina. As of the 2020 census, its population was 25,657. Its county seat and largest community is Edgefield. The county was established on March 12, 1785.