1. In order to classify, regulate, and restrict the location of trade and industry, and the location of buildings designated for specific uses; to regulate and limit the height and bulk of buildings hereafter erected or altered; to regulate and limit the intensity of the use of lot areas; and to regulate and determine the areas of yards, recreation, and open space within and surrounding those buildings, the city is hereby divided into ten districts. The use, height, and area regulations are uniform in each district.
2. Districts shall be known as:
   1. Residence districts.
      1. R-1, single-family residence district;
      2. R-2, medium density residence district; and
      3. R-3, multiple-family residence district.
   2. Non-residence districts.
      1. C-1, shopping center commercial district;
      2. C-2, neighborhood and service commercial district;
      3. C-3, office commercial district; and
      4. I-1, light industrial district.

The location and boundaries of the districts established by this title are set forth on the Official Zoning Map of the city, on file with the City Clerk. All notations, references and other information shown on the Official Zoning Map are incorporated by reference into this title and shall have the same force and effect as if set forth herein.

Wherever any uncertainty exists as to the boundary of any use district as shown on the Zoning Map incorporated herein by reference, the following rules shall apply.

1. Where district boundary lines are indicated as following streets, alleys, or similar rights-of-way, they shall be construed as following the center lines thereof.
2. Where district boundary lines are indicated as approximately following lot lines or section lines, those lines shall be construed to be the boundaries.
3. Where a lot held in one ownership, and of record at the effective date of this title, is divided by a district boundary line, the entire lot shall be construed to be within the less restricted district; provided that this construction shall not apply if it increases the area of the less restricted portion of the lot by more than 20%.
4. Where figures are shown on the Zoning Map between a street or property line and a district boundary line, they indicate that the district boundary line runs parallel to the street line or property line a distance therefrom equivalent to the number of feet so indicated, unless otherwise indicated.