Mo. Rev. Stat. § 445.050
Current with changes from the 2023 Legislative Session
When any such maps or plats shall be recorded, and by reason of the establishment of any new county, or the alteration of any new county lines, the city, town or village shall fall within a different county, such recorder shall transmit a certified copy of such plat or map to the recorder of the county, within which such city, town or village may be situated.
§ 445.050, RSMo
RSMo 1939 § 12812