Castle Airport — Merced, United States

MER identifies Castle Airport in Merced, California, built on the site of the former Castle Air Force Base, a Strategic Air Command bomber and refueling base that closed in 1995. Following the base's closure, MER was converted for civilian and commercial use, and it now hosts general aviation, cargo operations, flight training schools, and the Castle Air Museum, which displays historic military aircraft that once operated from the site. The airport's long runways, originally built for heavy bombers like the B-52, make it attractive for aviation testing, pilot training programs, and occasional charter or cargo flights serving California's Central Valley agricultural region. MER's dual heritage as a former SAC base and current civilian field makes it a distinctive aviation landmark in Merced County.