| County | County seat | Created | Origin |
| Abbeville | Abbeville | 1785 | Ninety Six District |
| Aiken | Aiken | 1871 | Barnwell, Edgefield, Lexington, and Orangeburg |
| Allendale | Allendale | 1919 | Barnwell and Hampton |
| Anderson | Anderson | 1826 | Pendleton District |
| Bamberg | Bamberg | 1897 | Barnwell |
| Barnwell | Barnwell | 1798 | Orangeburg |
| Beaufort | Beaufort | 1769 | 1769 Judicial District |
| Berkeley | Moncks Corner | 1882 | Charleston |
| Calhoun | St. Matthews | 1908 | Lexington and Orangeburg |
| Charleston | Charleston | 1769 | 1769 Judicial District |
| Cherokee | Gaffney | 1897 | Spartanburg, Union, and York |
| Chester | Chester | 1785 | Camden District |
| Chesterfield | Chesterfield | 1798 | Cheraws District |
| Clarendon | Manning | 1855 | Sumter |
| Colleton | Walterboro | 1800 | Charleston |
| Darlington | Darlington | 1785 | Cheraws District |
| Dillon | Dillon | 1910 | Marion |
| Dorchester | St. George | 1868 | Berkeley and Colleton |
| Edgefield | Edgefield | 1785 | Ninety-Six District |
| Fairfield | Winnsboro | 1785 | Camden District |
| Florence | Florence | 1888 | Clarendon, Darlington, Marion, and Williamsburg |
| Georgetown | Georgetown | 1769 | 1769 Judicial District |
| Greenville | Greenville | 1798 | Washington District |
| Greenwood | Greenwood | 1897 | Abbeville and Edgefield |
| Hampton | Hampton | 1787 | Beaufort |
| Horry | Conway | 1801 | Georgetown |
| Jasper | Ridgeland | 1912 | Beaufort and Hampton |
| Kershaw | Camden | 1798 | Claremont, Fairfield, Lancaster, and Richland |
| Lancaster | Lancaster | 1798 | Camden District |
| Laurens | Laurens | 1785 | Ninety-Six District |
| Lee | Bishopville | 1902 | Darlington, Kershaw, and Sumter |
| Lexington | Lexington | 1804 | Orangeburg |
| Marion | Marion | 1800 | Georgetown |
| Marlboro | Bennettsville | 1798 | Cheraws District |
| McCormick | McCormick | 1914 | Abbeville, Edgefield, and Greenwood |
| Newberry | Newberry | 1785 | Ninety-Six District |
| Oconee | Walhalla | 1868 | Pickens |
| Orangeburg | Orangeburg | 1769 | 1769 Judicial District |
| Pickens | Pickens | 1826 | Pendleton District |
| Richland | Columbia | 1799 | Camden District |
| Saluda | Saluda | 1896 | Edgefield |
| Spartanburg | Spartanburg | 1785 | Ninety-Six District |
| Sumter | Sumter | 1798 | Claremont, Clarendon, and Salem |
| Union | Union | 1798 | Ninety-Six District |
| Williamsburg | Kingstree | 1802 | Georgetown District |
| York | York | 1798 | Camden District |
The following units were formed of men from across the state or the organization of the unit is unknown.
