(1) If it appears by such census that the city or town contains the requisite population to be advanced, the council must thereupon by resolution declare, as the case may be, that:
(a) the town is advanced to a city of the first, second, or third class;
(b) a city of the third class is advanced to a city of the second or first class; or
(c) a city of the second class is advanced to a city of the first class.
(2) The city or town council must file a certified copy of such resolution in the office of the county clerk of the county and in the office of the secretary of state. Whereupon such town becomes a city of the first, second, or third class; a city of the third class becomes a city of the second or first class; and a city of the second class becomes a city of the first class, as the case may be, to be governed under the provisions of this code relative to cities and towns.