Mo. Rev. Stat. § 313.630
In lieu of any state or local sales tax on the gross receipts from admissions paid by persons attending the races and in lieu of any state or local amusement or entertainment tax, there is hereby imposed on each organization licensed to conduct horse races under the provisions of sections 313.510 to 313.710 a tax equal to ten percent of all moneys received each day from admissions paid by persons attending the races for deposit in the state treasury to the credit of the general revenue fund. The general assembly shall appropriate money from general revenue, up to one-half of the amount credited annually pursuant to this section, to municipalities and counties in the area in which races are conducted to assist the funding of services and facilities required by the conduct of racing in such municipality or county. Any county or municipal racing authority shall be subject to the rules and regulations of the commission.
§ 313.630, RSMo