N.C. Gen. Stat. § 160A-22
The current city boundaries shall at all times be drawn on a map, or set out in a written description, or shown by a combination of these techniques. This delineation shall be retained permanently in the office of the city clerk. Alterations in these established boundaries shall be indicated by appropriate entries upon or additions to the map or description made by or under the direction of the officer charged with that duty by the city charter or by the council. Copies of the map or description reproduced by any method of reproduction that gives legible and permanent copies, when certified by the city clerk, shall be admissible in evidence in all courts and shall have the same force and effect as would the original map or description. The council may provide for revisions in any map or other description of the city boundaries. A revised map or description shall supersede for all purposes the earlier map or description that it is designated to replace.
N.C. Gen. Stat. § 160A-22