N.C. Gen. Stat. § 160A-58.61
Whenever the limits of a municipality are enlarged in accordance with the provisions of this Part, it shall be the duty of the mayor of the municipality to cause an accurate map of such annexed territory, together with a copy of the ordinance duly certified, to be recorded in the office of the register of deeds of the county or counties in which such territory is situated and in the office of the Secretary of State. The documents required to be filed with the Secretary of State under this section shall be filed not later than 30 days following the effective date of the annexation ordinance. All documents shall have an identifying number affixed thereto and shall conform in size in accordance with rules prescribed by the Secretary. Failure to file within 30 days shall not affect the validity of the annexation. Any annexation shall be reported as part of the Boundary and Annexation Survey of the United States Bureau of the Census.
N.C. Gen. Stat. § 160A-58.61