Each city and incorporated village is hereby authorized and empowered to create a commission to be known as the city or village planning commission. Such commission shall be so created in incorporated villages by resolution of the trustees, in cities by ordinance of the common council, except that in cities of the first class, having more than a million inhabitants, it shall be by resolution of the board of estimate and apportionment or other similar local authority. In cities of the first class such commission shall consist of not more than eleven, in cities of the second class of not more than nine, in cities of the third class and incorporated villages of not more than seven members. Such ordinance or resolution shall specify the public officer or body of said municipality that shall appoint such commissioners, and shall provide that the appointment of as nearly as possible one-third of them shall be for a term of one year; one-third for a term of two years, and one-third for a term of three years; and that at the expiration of such terms, the terms of office of their successors shall be three years; so that the term of office of one-third of such commissioners, as nearly as possible, shall expire each year. All appointments to fill vacancies shall be for the unexpired term. Not more than one-third of the members of said commission shall hold any other public office in said city or village. In a county containing a population of over three hundred thousand one of the members of any such commission may reside outside of such village or city as the case may be.