The following rules shall apply to the boundaries of the various districts as shown on the Zoning District Map:
1. District boundary lines are either the centerlines of railroads, highways, streets, alleys, waterways or easements, or the boundary lines of sections, quarter sections, division of sections, tracts or lots, or such lines extended, unless otherwise indicated.
2. In areas not subdivided into lots and blocks, wherever a district is indicated as a strip adjacent to and paralleling a street or highway, the depth of such strips shall be in accordance with dimensions shown on the maps measured at right angles from the centerline of the street, highway or railroad right-of-way, and the length of the frontage shall be in accordance with dimensions shown on the maps from section, quarter-section, or division lines or center lines of streets, highways, or railroad rights-of-way unless otherwise indicated.
3. Where a district boundary line divides a lot as defined herein, the regulations for either portion of the lot may, in the owner's discretion, extend to the entire lot, but not more than twenty-five (25) feet beyond the boundary line of the district.