Mo. Rev. Stat. § 49.320: County commission may order buildings erected.

Whenever the county commission of any county thinks it expedient to erect any of the buildings aforesaid, the building of which is not otherwise provided for, and there are sufficient funds in the county treasury for that purpose, not otherwise appropriated, or the circumstances of the county will otherwise permit, they shall make an order for the building thereof, stating in the order the amount to be appropriated for that purpose.