All unplatted or unsubdivided property not specifically zoned otherwise is expressly zoned Class “N” 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 planning and zoning commission for approval. At the time of the approval, the city planning and zoning commission shall designate the recommended residential use district and any other use district for such subdivision. Thereafter, upon approval of the city commission and the filing of said approved plat for record, said subdivision shall be zoned by the city commission after notice and hearing as herein provided.