Mo. Rev. Stat. § 235.240

Any provision of the law to the contrary notwithstanding, no city, town or village shall annex a part of the territory of any district; but nothing herein shall be construed so as to prevent the annexation of the whole of the territory of a district by any city, town or village. If the entire district be annexed by any city, town or village as provided by law such municipality shall assume all debts, liabilities and obligations of the district; and title to all property, real, personal and mixed, of the district shall be transferred to and vested in such municipality.