Missouri constitution
Article VI: local government
Section 18(r)

Duplicate certificates shall be made, setting forth the adopted county constitution, and its ratification signed by the election authority of the county after canvassing election returns. One of the certified copies shall be deposited in the office of the secretary of state and the other, after being recorded in the records of the county, shall be deposited among the archives of the county and all courts shall take judicial notice thereof. Amendments shall be certified and deposited in the same way. Amendments to the county constitution shall be approved by the voters and shall become part of the county constitution at the time and under the conditions fixed in each amendment.