Mo. Rev. Stat. § 64.261
For any or all of said purposes, the unincorporated territory may be divided into districts of such number, shape and area as may be deemed best suited to carry out the purposes of sections 64.211 to 64.295, and shall be shown upon the plans or described in the regulations along with standards for their application. Within the districts, the erection, construction, reconstruction, alteration, repair or use of buildings, structures or land may be regulated and restricted. All the regulations shall be uniform for each class or kind of buildings or land uses throughout each district, but the regulations in one district may differ from those in other districts. The regulations shall be made in accordance with a comprehensive plan, and shall give reasonable consideration, among other things, to the existing use and character of the district, its suitability for particular uses, conserving the value of buildings and of existing development, and encouraging the most appropriate use of land throughout the county.
§ 64.261, RSMo