Mo. Rev. Stat. § 64.640
The county commission shall provide for the manner in which such regulations, restrictions and boundaries of such districts shall be determined, established and enforced, and from time to time amended, supplemented or changed within said unincorporated territory. In order to avail itself of the zoning powers conferred by sections 64.510 to 64.690, the county commission shall request the county planning commission to recommend the boundaries of the various original districts and appropriate regulations to be enforced therein. If there be no county planning commission the county commission shall appoint a county zoning commission whose personnel, length of terms and organization shall be the same as provided in section 64.520 for a county planning commission. Such zoning commission shall make a preliminary report and a proposed zoning order and shall hold public hearings thereon, and shall afford persons interested an opportunity to be heard. A hearing shall be held in each township affected by the terms of such proposed order, public notice of which hearing shall be given in the same manner as provided for the hearing in section 64.550. Such notice shall state the time and place of the hearing and the place where copies of the proposed report and proposed zoning order will be accessible for examination by interested parties. Such hearings may be adjourned from time to time. Within ninety days after the final adjournment of such hearings the zoning commission shall make a report and submit a proposed order to the county commission. The county commission may adopt the order with or without change or may refer it back to the zoning commission for further consideration and report. In case a written protest against the proposed zoning of any land lying within one and one-half miles of the corporate limits of any municipality having in effect an ordinance zoning property within the corporate limits of such municipality is made by resolution of the city council or board of trustees thereof and filed with the county commission, the county commission shall not adopt the proposed zoning of such land except by record vote of all members and after a statement of the reasons for such action shall be spread upon its minutes or records. In the preparation of its report and proposed zoning order the zoning commission may incur such expenditures as shall be authorized by the county commission.
§ 64.640, RSMo