Mo. Rev. Stat. § 234.310
All cities in this state now organized and operating under a special charter, or which are now or hereafter may be organized under the provisions of Section 19 of Article VI of the State Constitution, are hereby given the power and authority to build and construct bridges, viaducts and their approaches thereto; also to acquire, in whole or in part, by purchase, lease, gift, condemnation proceedings or otherwise, bridges, viaducts and the approaches thereto already constructed, together with the necessary lands, rights-of-way, easements, leaseholds, other property and rights, upon which any such bridge, viaduct, or its approach are now or may hereafter be constructed, operated and maintained by private parties, and to own, operate and maintain any such structure for public use, as and for a public highway for all kinds of vehicles, pedestrians, railroads and streetcars under such terms and conditions as the city may lawfully prescribe; and such cities are hereby empowered and authorized to condemn and pay for any or all such public improvements so constructed or acquired, together with the necessary lands, rights-of-way, easements, leaseholds, other property and rights, upon which any such bridge, viaduct or its approach are now or may hereafter be constructed, operated and maintained, in the manner aforesaid, either in whole or in part out of the general funds of the city, in whole or in part out of money raised from the sale of municipal bonds for that purpose, in whole or in part by special assessments.
§ 234.310, RSMo