Mo. Rev. Stat. § 60.335: Quarter-quarter sections, how established.

In subdividing a quarter-section into quarters, the land surveyor shall:

(1) First, establish the quarter-quarter, or sixteenth-section corners at points midway between the quarter-section and section corners or the center of the section, except on the last half mile of the lines closing on township boundaries, where they should be placed by proportionate measurement, as shown on the official government plat;

(2) Second, the center lines of the quarter-section will be run straight between opposite corresponding quarter-quarter, or sixteenth-section corners on the quarter-section boundaries. The intersection of the lines thus run will determine the legal center of the quarter-section.