S.C. Code Ann. § 31-7-120

Counties and municipalities through intergovernmental agreements may jointly adopt redevelopment plans and authorize obligations as provided under the provisions of this chapter and Chapter 6 of this title. Counties by intergovernmental agreement incorporated into individual county ordinances, may establish a multi-county or regional authority for both the establishing of a redevelopment plan and redevelopment projects if the documented economic impacts of projects extend beyond the boundaries of a single county. All actions to develop such plans and projects must be taken by the governing bodies of the respective counties participating in the grouping or authority pursuant to the contractual terms of the intergovernmental agreements establishing such groupings or authority.