Mo. Rev. Stat. § 226.799
Prior to the designation of a road or highway as a scenic byway pursuant to the provisions of section 226.797, the commission shall provide written notice of its intent to designate the road or highway as a scenic byway to newspapers of general circulation in the area or areas affected and to the governing body of each county and each municipality that has jurisdiction over all or part of the road or highway. Within thirty days after receipt of such notice, the governing body of each such county or municipality shall conduct a public hearing on the matter. Within ninety days after the receipt of the notice from the commission, each such governing body of a county or municipality, after such hearing, shall approve or reject the proposed designation of the road or highway as a scenic byway and notify the commission of its approval or rejection of the proposed scenic byway. The commission shall only designate a portion of a road or highway as a scenic byway if the governing body of the county or municipality containing that portion of the road or highway approves the proposed scenic byway as prescribed in this section.
§ 226.799, RSMo