Mo. Rev. Stat. § 49.530: Interest rate and maturity of bonds.

All bonds under the provisions of sections 49.520 to 49.580 may be issued bearing interest at a rate not exceeding six percent per annum, payable semiannually, and shall be executed in such manner and be payable at such time, not exceeding forty years from the date thereof, and at such places as the governing body of the county may require.