Mo. Rev. Stat. § 94.852: Boundary changes, procedure, city clerk's duties — tax effect on detached and added territory.

If any city, town, or village shall hereafter change or alter its boundaries, the city clerk of the municipality shall forward to the director of revenue, by registered mail, a certified copy of the ordinance adding or detaching territory from the municipality. The ordinance shall reflect the effective date thereof, and shall be accompanied by a map of the municipality clearly showing the territory added thereto or detached therefrom. Upon receipt of the ordinance and map, the tax imposed by sections 94.850 to 94.857 shall be effective in the added territory or abolished in the detached territory on the effective date of the change of the municipal boundary.