S.C. Code Ann. § 57-25-185

The Department of Transportation shall promulgate regulations consistent with Section 131(o), Title 23, United States Code, or such other provisions of Title 23 as may be appropriate, to allow signs, displays, and devices on federally-aided primary routes outside of nonurban areas which (1) provide directional information about goods and services in the interest of the traveling public and (2) are such that removal would work an economic hardship in such areas. Pursuant to Section 131(o), Title 23, United States Code, the department shall submit these regulations to the United States Secretary of Transportation for approval.