Mo. Rev. Stat. § 229.080

Whenever any citizen or citizens of any county shall subscribe any sum not less than fifty dollars, for the purpose of grading, tiling, ditching or surfacing any portion of any public road in such county, and shall deposit the same with the county treasurer of such county, the county commission may appropriate and pay out of the road funds of the county a like amount for the same purpose. The amount so subscribed shall be paid out only for such work as shall be designated by the subscribers thereof, and shall be expended under the direction and supervision of the county highway engineer.