All moneys levied and collected by the state by general state taxation for state highway purposes, or received from the sale of bonds, or appropriated for state highway purposes, shall be expended only in the laying out, marking, constructing, reconstructing, or maintaining public highways forming the trunk highway system and for the expenses of the Transportation Commission. However, twenty-five percent of all such moneys accruing to the state highway fund, other than from federal funds, may be used by the department in marking, constructing, reconstructing, repairing, or maintenance of highways and bridges of the state. The commission may promulgate rules, pursuant to chapter 1-26, to establish procedures for the application and approval of loans to local government highway jurisdictions. The jurisdictions may use the money for the marking, constructing, reconstructing, repairing, and maintenance of the highways and bridges of the state pursuant to terms and conditions determined by the commission.
SDCL 31-5-8