The streets and alleys as opened, laid out, surveyed and named on the official map of the townsite of Grass Valley, the townsite of South Grass Valley, and the townsite of West Grass Valley, so far as is included in the city, shall be public streets of the city, including those streets that are in the city and were at the time of annexation public streets within the unincorporated area and also those streets within the unincorporated area and also those streets that are added to the city system from time to time by subdivision development and accepted by the council. (Prior code § 21-1)