Mo. Rev. Stat. § 70.230: Procedure for exercising power.

Any municipality may exercise the power referred to in section 70.220 by ordinance duly enacted, or, if a county, then by order of the county commission duly made and entered, or if other political subdivision, then by resolution of its governing body or officers made and entered in its journal or minutes of proceedings, which shall provide the terms agreed upon by the contracting parties to such contract or cooperative action.