Mo. Rev. Stat. § 47.050

The county commission shall grant to each person so appointed a certificate thereof, under the seal of the county commission, appoint a time and place when and where the commissioners shall assemble, cause a notice thereof to be served on each commissioner, and cause advertisements to be put up by the sheriff in ten of the most public places in the county, one month before such meeting, notifying the inhabitants of the county of the time and purport of the meeting.