Mo. Rev. Stat. § 247.320
Any time after the filing of a petition for the organization of a district and before the day fixed for the hearing thereon, a petition may be filed in the office of the circuit clerk, wherein the petition for the organization of such district is pending, protesting against the creation of the proposed district. Such protesting petition shall be signed and filed by or on behalf of one or more voters of the district, and shall recite wherein the incorporation of the district will not promote the purposes as set forth in the original petition, or wherein sufficient facts have not been related to justify the incorporation of such district, and any other facts which may be useful to the court in determining whether or not such original petition shall be allowed.
§ 247.320, RSMo