Section 4
SEC. 4. (a) Incorporated municipalities shall be of four classes, according to the number of inhabitants. Municipalities of the first class shall be those which contain not less than twenty-five thousand inhabitants, and shall have eighteen councilors of the second class, those containing eighteen thousand and less than twenty-five thousand inhabitants, and shall have fourteen councilors of the third class, those containing ten thousand and less than eighteen thousand inhabitants, and shall have ten councilors; of the fourth class, those containing less than ten thousand inhabitants, and shall have eight. (b) Municipalities of less than two thousand inhabitants may be incorporated under the provisions of this Act, or may, upon petition signed by a majority of qualified electors thereof, be attached as a barrio to an adjacent and incorporated municipality, if the council of the latter shall grant said petition. (c) A barrio or barrios with an aggregate population of more than two thousand may be incorporated under the provisions of this Act as a separate municipality, upon the granting by the Commission of a petition signed by two-thirds of the qualified electors thereof. (d) In case of controversy, the Commission shall determine to which class a town, shall belong, and thereafter, if its population shall sufficiently increase or diminish, it shall pass to a higher or lower class by order of the provincial board.