Mo. Rev. Stat. § 50.070

The county commission in counties of class one, class three and class four may, by resolution, duly passed by a majority of the commissioners thereof, and upon order of said commission, issue negotiable notes payable in one year or less from the date of issue out of the current county revenues, respectively, to be derived from taxes or other revenues of the county of the year in which said notes are issued; but where taxes are levied for special purposes or revenues derived from special sources other than taxes resulting from a levy, the notes issued against the anticipated revenues derived therefrom shall bear a statement that the said notes are to be paid out of said special taxes or special revenues.