Idaho Code § 43-109
Such board shall also make an order dividing the district into not less than three (3) nor more than seven (7) divisions of as nearly equal size as practicable, which shall be numbered first, second, third, etc., and one (1) director, who shall be an elector and resident in the division, shall be elected from each division of the district at large, except that in districts of three thousand (3,000) acres or less the directors may be elected from qualified electors, holding title or evidence of title to land in the district and residing in the county in which some portion of the district is located. The number of divisions into which said district shall be divided shall be specified in the petition for the organization of the district, and if not otherwise specified shall be three.
Idaho Code § 43-109