Iowa Code § 468.505: Record and plat of election districts.

At the time of making a division into election districts, as provided in section 468.504, the board or boards shall designate by congressional divisions, subdivisions, metes and bounds, or other intelligible description, the lands embraced in each election district, and the auditor, or auditors if more than one county shall make a plat thereof in the drainage record of the district indicating thereon the boundary lines of each election district, numbering them, one, two, and three, respectively.