S.C. Code Ann. § 57-25-170

The commission may provide within the right-of-way for areas at appropriate distances from interchanges on the interstate system and controlled access roads on the federal-aid primary system on which signs, displays, and devices giving specific information in the interest of the traveling public may be erected and maintained under standards and regulations authorized to be adopted and promulgated by the commission. The standards and regulations may provide for cooperative agreements between the Department of Transportation and private interests for the use and display of names for FOOD, LODGING, and GAS information signs on the highway right-of-way.