Whenever any area is annexed to the City of Ionia one of the following conditions will apply:
(a) Land that is zoned previous to annexation shall be classified as being in whichever district of this Zoning Code most closely conforms to the zoning that existed prior to annexation, such classification to be recommended by the Planning Commission to the City Council, and the Council shall approve the same by resolution.
(b) Land not zoned prior to annexation shall be automatically classified as an R-1 District until a Zoning Map for said area has been adopted by the City Council. The Planning Commission shall recommend the appropriate zoning districts for such area within three months after the matter is referred to it by the City Council, or within one year after the annexation is completed.
(1975 Code §5.23)