Mo. Rev. Stat. § 182.800
The governing board of any free library district may invest funds of the district. The board may invest the funds in either open time deposits for ninety days or certificates of deposit in a depositary selected by the board, if the depositary has deposited securities under the provisions of sections 110.010 and 110.020; or in bonds, redeemable at maturity at par, of the state of Missouri, of the United States, or of any wholly owned corporation of the United States; or in other short term obligations of the United States. No open time deposits shall be made or bonds purchased to mature beyond the date that the funds are needed for the purpose for which they were received by the district. Interest accruing from the investment of funds in such deposits or bonds shall be credited to the library district fund from which the money was invested.
§ 182.800, RSMo