Mesa is a city in Maricopa County, Arizona and part of the Phoenix-Mesa-Scottsdale Metropolitan Area. It is the third-largest city in Arizona, after Phoenix and Tucson.

Mesa is one of the United States' fastest-growing cities, and currently ranks as the 41st-largest. In 2005 The City of Mesa website estimated the city's population at 451,860. Though a suburban city, Mesa actually has a larger population than better-known cities such as St. Louis, Missouri and Pittsburgh, Pennsylvania. Despite its large population, Mesa has a decidedly bedroom-community, sprawl-like character. Its downtown is minimal, and there are very few buildings in Mesa with more than two stories. Nevertheless, the recently completed Mesa Arts Center may help invigorate downtown Mesa. The city is also home to many gated retirement communities, which may explain the large percentage of senior citizens in the population.

Mesa was founded in January 1878 by Mormon (LDS) pioneers and its population is still roughly one-quarter Mormon. Since the city's population is well over twice that of Salt Lake City (which is now only about 45 percent LDS), Mesa has a greater Mormon population than any other single city in the world. The LDS Church operates one of its oldest temples in Mesa (the Mesa Arizona Temple), and the city is a hub of sorts for Latter-day Saints residing in the Phoenix Metro area.

Mesa's residents exhibit jarring economic diversity, with low-income areas and mobile-home parks somewhat close to high-scale neighborhoods with extravagant custom homes.