S.C. Code Ann. § 6-7-1220

Counties and municipalities may establish official maps to reserve future locations of any street, highway, or public utility rights-of-way, public building site or public open space for future public acquisition and to regulate structures or changes in land use in such rights-of-way, building sites or open spaces. This authority is declared necessary in order to promote and preserve the public safety, economy, good order, appearance, convenience, prosperity, and general welfare and is one of the several instruments of land use control authorized by this chapter for the implementation of comprehensive plans, or parts thereof, adopted in accordance with the provisions of this chapter.