S.C. Code § 4-3-20
Aiken County is bounded as follows: on the northwest by Edgefield and Saluda Counties from which it is divided by a straight line commencing at the mouth of Fox's Creek, where it empties into Savannah River, and running thence to where the south branch of Chinquapin Falls Creek (a tributary of the North Edisto River) intersects the Saluda and Lexington line; on the northeast by Lexington County, from which it is divided by said creek to where it empties into the North Fork of the Edisto River and by the said North Fork to where the dividing line between Lexington and Orangeburg Counties (running from Big Beaver Creek to the North Fork of the Edisto) touches said river; on the southeast by Orangeburg and Barnwell Counties, from which it is divided by a straight line established by J. Seth Mixon, deputy surveyor, running by A. J. Weathersbee's old mill to the Savannah River, at a point below the mouth of the Upper Three Runs Creek, said survey having been made under act of Assembly approved March 14 1874; on the southwest by Georgia, from which it is separated by the Savannah River.
S.C. Code § 4-3-20