Mo. Rev. Stat. § 95.125
Any city, whether organized under the general laws of this state or by special charter or by constitutional charter, by a vote of the constitutionally required percentage of the voters thereof voting thereon, may become indebted, not exceeding in the aggregate an additional ten percent of the value of the taxable tangible property therein as shown by the last completed assessment for state and county purposes, for the purpose of acquiring rights-of-way, constructing, extending and improving the streets and avenues and acquiring rights-of-way, constructing, extending and improving sanitary or storm sewer systems. The governing body of such city may provide that any portion or all of the cost of any such improvement be levied and assessed by such governing body on property benefitted by such improvement, and, when so provided, such city shall collect any special assessments so levied and shall use the same to reimburse the city for the amount paid or to be paid by it on the bonds of the city issued for such improvement.
§ 95.125, RSMo