Mo. Rev. Stat. § 72.100
Provided, that when any city, town or other area is or may be situated on the county line, and in two counties, the petition shall be signed by a number of voters equal to fifteen percent of the votes cast in the last gubernatorial election in the area proposed in each county to be incorporated of such city, town or other area in each county, and presented to the governing body of each county, and designating that each of the two governing bodies equally shall designate the officers therefor. If the governing body of each county shall be satisfied that a number of voters equal to fifteen percent of the votes cast in the last gubernatorial election in the area proposed in each county to be incorporated have signed such petition, the governing bodies of each county shall submit the question to the voters. If a majority of the voters voting on the question, of each of the counties in such city or town, vote for incorporation, the governing bodies of each county shall declare such city or town incorporated and the inhabitants thereof shall thenceforth be a body politic and incorporate, by the name and style of "the city of ______", or "the town of ______", and provided further, that appeals taken from the decision of the mayor, judge or other officer before whom any cause is tried, acting for said city, town or other area may be sent to the circuit court of either county wherein such city or town is situated, as may be specified in the order granting such appeal.
§ 72.100, RSMo