S.C. Code Ann. § 57-11-250

For the payment of the principal of and interest on all state highway bonds (whether now outstanding or hereafter issued), as the same shall come due, there shall be pledged the full faith, credit, and taxing power of the State of South Carolina and, in addition thereto, all of the monies derived from all sources of revenue which may be forthwith used by the State Treasurer, without further action of the commission, for the payment of the principal and interest of state highway bonds, as the same respectively mature.