Area code 520 covers southeastern Arizona, including cities like Tucson, Sierra Vista, and Nogales. Introduced in 1995 as a split from 602, 520 captures a mix of desert landscapes, military presence, and growing tech and healthcare sectors. Tucson, the largest city in the area, is home to the University of Arizona and boasts a strong aerospace, optics, and defense industry ecosystem. Raytheon, Davis-Monthan Air Force Base, and numerous tech startups contribute to the local economy. The region also borders Mexico, making it an important corridor for cross-border commerce and logistics. Sierra Vista supports Fort Huachuca, a key military installation specializing in communications and intelligence. A 520 number lends regional familiarity and local trust across Southern Arizona, making it ideal for businesses in education, logistics, security, and healthcare.