The Arizona Sun Corridor, shortened Sun Corridor, is a megaregion, or megapolitan area, in the southern area of the U.S. state of Arizona - comprising approximately 85 percent of the state's population. The Sun Corridor is comparable to Indiana in both size and population. It is one of the fastest growing conurbations in the country. The largest metropolitan areas are the Phoenix metropolitan area – Valley of the Sun, and the Tucson metropolitan area – The Old Pueblo. The regions' populace is nestled in the valley of a desert environment. Similar to Southern California, the urban area extends into Mexico, reaching the communities of Heroica Nogales and Agua Prieta.
Its population is composed of five metropolitan areas: Phoenix, Tucson, Prescott, Sierra Vista-Douglas and Nogales. Of these, two are metropolitan areas with over 1,000,000 residents: the Phoenix metropolitan area with 4.85 million residents and the Tucson metropolitan area with over 1 million residents. The Arizona Sun Corridor is made up of all of Maricopa, Pinal and Pima counties, along with parts of Yavapai, Santa Cruz and Cochise counties. It is home to over 86 percent of Arizona's population.