The annual town election, scheduled for March 26, will have only one contested race. Two residents are vying for the School Committee seat being vacated by Christine Allen, who announced last month that she would not run for reelection. Mark Mezzina and Zora Warren have been certified as candidates for School Committee, according to the town clerk’s office. Also certified as candidates are incumbents Rosemary Connolly Smedile, who is seeking another three-year term on the Board of Selectmen, and Mary Beth Soucy, who is seeking reelection to the North Andover Housing Authority, which has five-year terms. Both women are running unopposed.