Missouri Constitution
Article VI - Local Government
Section 30(a) Powers conferred with respect to intergovernmental relations— procedure for selection of board of freeholders.

—The people of the city of St. Louis and the people of the county of St. Louis shall have power (1) to consolidate the territories and governments of the city and county into one political subdivision under the municipal government of the city of St. Louis; or, (2) to extend the territorial boundaries of the county so as to embrace the territory within the city and to reorganize and consolidate the county governments of the city and county, and adjust their relations as thus united, and thereafter the city may extend its limits in the manner provided by law for other cities; or, (3) to enlarge the present or future limits of the city by annexing thereto part of the territory of the county, and to confer upon the city exclusive jurisdiction of the territory so annexed to the city; or, (4) to establish a metropolitan district or districts for the functional administration of services common to the area included therein; or, (5) to formulate and adopt any other plan for the partial or complete government of all or any part of the city and the county. The power so given shall be exercised by the vote of the people of the city and county upon a plan prepared by a board of freeholders consisting of nineteen members, nine of whom shall be electors of the city and nine electors of the county and one an elector of some other county. Upon the filing with the officials in general charge of elections in the city of a petition proposing the exercise of the powers hereby granted, signed by registered voters of the city in such number as shall equal three percent of the total vote cast in the city at the last general election for governor, and the certification thereof by the election officials to the mayor, and to the governor, then, within ten days after the certification the mayor shall, with the approval of a majority of the board of aldermen, appoint the city’s nine members of the board, not more than five of whom shall be members of or affiliated with the same political party. Each member so appointed shall be given a certificate certifying his appointment signed by the mayor and attested by the seal of the city. Upon the filing with the officials in general charge of elections in the county of a similar petition signed by registered voters of the county, in such number as shall equal three percent of the total vote cast in the county at the last general election for governor, and the certification thereof by the county election officials to the county supervisor of the county and to the governor, within ten days after the certification, the county supervisor shall, with the approval of a majority of the county council, appoint the county’s nine members of the board, not more than five of whom shall be members of or affiliated with the same political party. Each member so appointed shall be given a certificate of his appointment signed by the county supervisor and attested by the seal of the county.

Source: Const. of 1875, Art. VI, Sec. 26 (Adopted November 4, 1924) (Amended November 8, 1966)