Mo. Rev. Stat. § 234.340
All cities in this state having one hundred thousand inhabitants or over are hereby given the power and authority to build or acquire, by purchase, lease, gift or otherwise, within their corporate limits or within a reasonable distance outside thereof, a bridge or bridges, or a tunnel or tunnels, for public use by railroads, streetcars, vehicles of all kinds and pedestrians, over or under rivers and streams in Missouri or those forming a boundary between this and other states, and to acquire, hold, use and retain, by purchase, lease, gift or otherwise, land to be used for approaches for and in the construction, operation and maintenance of said bridge or bridges, tunnel or tunnels, in this and other states, and to maintain, use and operate said bridge or bridges, tunnel or tunnels, either as toll or free bridges or tunnels, as may by said cities be deemed expedient.
§ 234.340, RSMo