Mo. Rev. Stat. § 182.280

Whenever the board of trustees of any public library acquires a lot or tract of land, and the board determines that it is not judicious to erect the library building upon the lot, the board may sell or exchange the lot and to use the proceeds of the sale or exchange for the purposes of a site for a library building, or for the erection of a library building, on any other land purchased or leased by or donated to the board and which it may deem suitable for the building. Sections 182.260, 182.270 and 182.280 shall not apply to cities under ten thousand inhabitants.