Mo. Rev. Stat. § 534.240: Extent of claim where there has been no survey.

Where no legal survey has been made of such possession, the improvement of the person entitled to the possession shall be in the middle of the tract as near as may be, making the survey as near in a square as may be, not to interfere with any established survey or line, or any conditional line agreed upon by the adjoining proprietors or possessors.