All unplatted or unsubdivided property is expressly zoned class "A" district. At the time the owner of any such unplatted and unsubdivided property proposes to subdivide and/or develop the same as a subdivision or otherwise, he shall submit a plat of the proposed subdivision to the city zoning and planning board for public hearing and approval or rejection.

At the time of the approval, the zoning and planning board shall designate the recommended residential use district for such subdivision. Thereafter, upon approved of the city commission and the filing of said approval plat for record, said subdivision shall be zoned by the city commission.