The commission may adopt the plan as a whole by a single resolution or may by successive resolutions adopt successive parts of the plan, said parts corresponding with major geographical sections or divisions of the municipality or with functional subdivisions of the subject matter of the plan and may adopt any amendment or extension thereof or addition thereto.
Before the adoption of the plan or any such part, amendment, extension or addition, the commission shall hold at least one public hearing thereon, notice of the time and place of which shall be given by one publication in a newspaper of general circulation in the municipality and in the official gazette, if any, of the municipality; provided, that the planning commission may dispense with such public hearing prior to the approval or disapproval of a plan when the municipal governing body to whom the plan will be submitted will be required to hold a public hearing, and give notice thereof before the plan can be adopted by such municipality.
The adoption of the plan or of any such part or amendment or extension or addition shall be by resolution of the commission carried by the affirmative votes of not less than six members of the commission or, in any city having a 16-member planning commission as provided in subsection (a) of Section 11-52-3, by the affirmative votes of not less than 12 members of the commission. The resolution shall refer expressly to the maps and descriptive and other matters intended by the commission to form the whole or part of the plan, and the action taken shall be recorded on the map and plan and descriptive matter by the identifying signature of the chairman or secretary of the commission. An attested copy of the plan or part thereof shall be certified to the governing body and to the county probate judge.