After serving for almost 18 years, Mayor William Scanlon will not run for another term in office. First elected in November 1993, Scanlon, 73, has been through 10 contested campaigns. He won nine of the races, but was defeated in 2001 by Thomas Crean. He regained the office two years later and has served since then. Scanlon said he decided not to run for reelection about two weeks ago, but chose to “sit on it for a week” after the Boston Marathon terrorist bombings on April 15.