Before any improvement district shall create any zone or district or regulate or restrict the use of buildings or land therein, the governing body shall approve a proposed zoning resolution fixing the boundaries of the proposed zoning districts and the regulations and restrictions to be imposed therein. Such proposed zoning resolution together with a notice of a public hearing thereon shall be published once each week for two consecutive weeks in the official county newspaper. At least 20 days shall elapse between the date of the last publication of such resolution and notice and the public hearing held thereon. Such hearing may be adjourned from time to time and at the conclusion of the same the governing body may adopt such zoning resolution as proposed or may revise or amend and adopt the same as revised or amended. The boundaries of zones or districts may be set out upon a map incorporated and published as a part of the zoning resolution. Upon adoption such zoning resolution shall be published once in the official county newspaper. For the purpose of defining the boundaries of zones or districts, the governing body shall publish a map upon which boundaries shall be fixed.

The governing body may from time to time supplement, change or generally revise the boundaries or regulations contained in any zoning resolution. Any amendments or changes made in any zoning resolution shall be made by resolution in the manner, and after notice and hearing, as prescribed for the adoption of the original zoning resolution. If a protest against any such amendment or change in any zoning resolution is filed in the office of the county clerk within 14 days after the date of the conclusion of the hearing duly signed and acknowledged by the owners of 20% or more of any property proposed to be rezoned or by the owners of 20% of the total area excepting public streets and ways which is located within 200 feet of the boundaries of the property proposed to be rezoned, the resolution adopting such amendment or change shall not be passed except by unanimous vote of the members of the governing body of the district.