S.C. Code Ann. § 11-43-550
For the payment of the principal of and interest on all transportation infrastructure bonds, whether or not outstanding or hereafter issued, as they come due, there is pledged the full faith, credit, and taxing power of this State. In addition to the full faith, credit, and taxing power, there also may be pledged such revenue as may be available to the board and the State Treasurer is authorized to use such revenue when pledged, without further action of the board, for the payment of the principal and interest on transportation infrastructure bonds as the same respectively mature.