Mo. Rev. Stat. § 205.971
The board of aldermen or other governing body of a city not within a county and the county commission or other governing body of the county, except for a county of the first classification having a charter form of government containing in part a city with a population of more than three hundred fifty thousand inhabitants, or a county of the first classification having a charter form of government with a population of at least nine hundred thousand inhabitants may, upon approval of a majority of the qualified voters of such city or county thereon, levy and collect a tax not to exceed four mills per dollar of assessed valuation upon all taxable property within the city or county for the purpose of establishing and maintaining the county sheltered workshop, residence, facility and/or related services. The county commission or other governing body of a county of the first classification having a charter form of government containing in whole or part a city with a population of more than three hundred fifty thousand inhabitants, or a county of the first classification having a charter form of government with a population of at least nine hundred thousand inhabitants may, upon approval of a majority of the qualified voters of such county or city voting thereon, levy and collect a tax not to exceed two mills per dollar of assessed valuation upon all taxable property within such county or city for the purpose of establishing and maintaining the county or city sheltered workshop, residence, facility and/or related services. The tax so levied shall be collected along with other county taxes, or in the case of a city not within a county, with other city taxes, in the manner provided by law. All funds collected for this purpose shall be deposited in a special fund and shall be used for no other purpose. Deposits in the fund shall be expended only upon approval of the board.
§ 205.971, RSMo