S.C. Code Ann. § 6-21-5

In furtherance of the powers granted to the counties of this State pursuant to the provisions of Section 4-9-30, and Section 6-21-10 et seq., of the 1976 Code, each of the counties of this State is authorized to establish transportation authorities and to finance, following the public hearing and referendum required in Chapter 37, Title 4, the cost of acquiring, designing, constructing, equipping and operating highways, roads, streets, and bridges, and other transportation-related projects, either alone or in partnership with other governmental entities including, but not limited to, the South Carolina Department of Transportation.