Mo. Rev. Stat. § 231.240
Whenever the inhabitants of any road district of any county of this state having heretofore adopted or which may hereafter adopt township organization may desire to adopt the contract system of working roads in such road district, it may be accomplished in the following manner: Upon the receipt by the township clerk of a petition from a majority of the resident householders of such road district, residing outside of an incorporated city, town or village, setting forth the facts, the township board of directors shall at its next regular meeting, if such meeting be held within thirty days after the receipt by the township clerk of such petition, and otherwise at a special meeting of the township board to be held not later than thirty days after the receipt of such petition, order the adoption of said system in said road district. The township clerk shall enter in the record of the township board all of the proceedings concerning the adoption of said contract system and shall declare, by publication, the adoption of said system in such road district.
§ 231.240, RSMo