The provisions of this Zoning Code shall apply within the corporate limits of the City as now or hereafter fixed. District boundaries are shown on the “Official Zoning Map of the City of Postville, Iowa” said map being as much a part of this Zoning Code as if fully described herein. Where uncertainty exists as to boundaries, the following rules shall apply:

   1.   Where districts are bounded approximately by street or alley lines, the centerline of streets or alleys shall be construed to be the boundaries.

   2.   Where districts are bounded approximately by lot lines, said lot lines shall be construed to be the boundaries.

   3.   Where districts are not bounded approximately by either streets, alleys, or lots, boundaries shall be determined by the Planning and Zoning Commission.

   4.   Whenever any street, alley, or other public way is officially vacated, the zoning district on either side shall be automatically extended to the centerline of said vacation.