Mo. Rev. Stat. § 60.140: Lands divided by county lines, by whom surveyed.

In case any person own or claim lands where the same are divided by a county line, the person owning or claiming such lands, and wishing to have the same surveyed, may apply to the surveyor of any county in which any part of such land is situate; and, on such application being made, the surveyor is authorized and required to make such survey, which shall be as valid as though such lands were situate entirely in one county.