There are 46 counties in South Carolina. As of 2019, South Carolina's most populous county is Greenville County, home of Greenville, with a population of 506,837. This represents growth of 11.95% since the last census. Greenville is followed by Richland County (411,592), Charleston County (401,438), Horry County (333,268), and Spartansburg County (306,854). These are the only counties of South Carolina with a population of more than 300,000 and all have experienced population growth of at least 6%. Of these counties, Horry County has experienced the most rapid growth of 23.23% since the census.
The least populated county in South Carolina is Allendale County with a population of 9,002, down 13.02% from the 2010 census. McCormick County follows closely behind at 9,545 residents which represents a population growth of -6.54%. Other small counties in South Carolina with fewer than 15,000 people are Bamberg County (14,381) and Calhoun County (14,704). Both counties have also experienced negative population growth. All six counties in South Carolina with fewer than 20,000 residents have declined in population since the census.
Horry County, the 4th most populated county in South Carolina, has experienced the most rapid growth since the census at 23.23% to a population of 333,268. Two other counties topped 20% growth: Berkeley County (21.77%) and Lancaster County (20.24%). Only five other counties experienced growth above 12%: York County (17.44%), Beaufort County (14.74%), Charleston County (14.36%), Jasper County (14.15%), and Dorchester County (13.81%).