Mo. Rev. Stat. § 231.370
Contracts for the laying of such sidewalks, curbs, gutters, combinations of curb and gutter and roadways as are provided for in section 231.360, shall be authorized and let by the aforesaid county commission to the lowest and best bidder therefor, said commission first giving notice thereof by publication, which notice shall be published for fifteen days in a daily newspaper or for three insertions in a weekly newspaper at the county seat of such county. Said notice must contain a summary of the specifications showing the kind of material required, the width and the thickness of such sidewalk, curbs, gutters, combinations of curb and gutter and roadway and the manner of paying therefor, together with the time and place where said specifications may be examined; provided, that all sidewalks constructed under the provisions of sections 231.360 to 231.390, shall be of uniform width not less than four feet in any one block, and the general specifications of such sidewalk or sidewalks shall be determined by the county commission in conformity with the wishes of the petitioners.
§ 231.370, RSMo