Area code 520 serves southern Arizona, including the metropolitan area of Tucson (Arizona’s second-largest city) and other communities such as Casa Grande, Nogales, Yuma (before 2001), and Sierra Vista. The 520 code was created on March 19, 1995, when Arizona’s original 602 area code was split – 520 was assigned to all parts of Arizona outside the Phoenix metro, which had become too populous for a single code. Originally, 520 spanned from the Mexican border up through northern Arizona (covering cities like Flagstaff and Yuma as well as Tucson). Due to continued growth, however, the northern and western portions of the 520 territory were carved out in 2001 to form area code 928, leaving 520 primarily to cover Tucson and the southeastern part of the state. Today, area code 520 is synonymous with the Tucson area and surrounding counties – it encompasses the state’s southern desert region and border communities, from the academic and cultural hub of Tucson to the historic Old West town of Tombstone. The 520 code has no overlay and still provides ample numbers for southern Arizona, illustrating that outside the Phoenix area, one area code has been sufficient for this region’s needs