All unimproved or agricultural territory that may hereafter be annexed to the City shall be considered as lying in the A1 Agricultural District until such classification shall be changed as provided by this chapter. Any improved property that is annexed into the City shall be zoned according to the zoning district that most nearly describes either its present use or the use proposed by the Comprehensive Development Plan. The Planning and Zoning Commission and the City Council shall establish this zoning at the time of annexation.