Meridian is the second-largest city in Ada County, Idaho, USA, and the third-largest in the state. As of July 2007, the population estimate of Meridian was 64,642. Having recently surpassed the eastern Idaho cities of Pocatello and Idaho Falls, the 2007 estimates placed Meridian as the third-largest city in Idaho behind Boise and Nampa, all in the Treasure Valley. Meridian is the state's fastest-growing city, with a 81.5 percent increase in population since 2000. The Meridian School District is the largest in the state. Meridian is part of the Boise metropolitan area.