Phoenix (/ˈfiːnɪks/ FEE-niks) is the capital and most populous city of the U.S. state of Arizona, with 1,608,139 residents as of 2020. It is the fifth-most populous city in the United States and the most populous state capital in the country. Phoenix is the most populous city of the Phoenix metropolitan area, also known as the Valley of the Sun, which in turn is part of the Salt River Valley and Arizona Sun Corridor.