Mo. Rev. Stat. § 71.140

Every commission, board, committee, officer or other governing body of any city or town shall purchase and use only those materials, products, supplies, provisions and other needed articles produced, manufactured, compounded, made or grown within the state of Missouri, when they are found in marketable quantities in the state and are of a quality suited to the purpose intended and can be secured without additional cost over foreign products or products of other states; provided, however, that quality and fitness of articles shall be considered in purchasing or letting contracts for articles herein mentioned.