Mo. Rev. Stat. § 231.400
The county commissions in all counties of the second class shall have the power to provide for and require the building of sidewalks and roadways including grading therefor, along any street, avenue, road or highway in any unincorporated village or residence district in such county by and at the expense of the owner of the lots fronting on such street, avenue, road or highway, along the distance improved in proportion to the front feet, whenever a petition therefor shall be filed with the county commission signed by a majority of the owners resident on such street, avenue, road or highway, and liable to taxation therefor, which sidewalks and roadways shall be constructed in such manner and of such dimensions as are herein provided.
§ 231.400, RSMo