(a) If an area is annexed to or disannexed from a municipality, the mayor or other presiding officer of the governing body of the municipality shall, within 30 days after the date of preclearance under Section 5, Federal Voting Rights Act (42 U.S.C. Sec. 1973c), of the annexation or disannexation, send to the county clerk of each county in which the municipality is located a certified copy of documents showing the change in boundaries.
(b) The county shall promptly correct to reflect the change in municipal boundaries any official county map kept by the county that would be affected by the change.