Miss. Code Ann. § 65-11-21

The State Highway Commission is hereby authorized and directed to prepare all necessary surveys, plans, specifications, and estimates for all projects upon county highways, to furnish engineering and technical assistance for the preparation of such surveys, plans, specifications, and estimates, and to supervise the construction of all projects upon county highways under the provisions of Sections 65-11-1 through 65-11-37; the cost and expense of such surveys, plans, specifications, estimates, and the supervision of projects shall be paid from the federal aid or state appropriated funds allocated for such project, or from any other funds that the county might have available for such purpose.