The City of Phoenix is the largest and most populous city in the state of Arizona. It is also the state capital and the largest state capital in the United States in terms of population. Phoenix is the only state capital with a population of more than a million. It is also the county seat of Maricopa County. It is the largest city in the American Southwest and the Mountain Time Zone as well as the second largest city in the Western United States after Los Angeles, California. It is the region's primary political, cultural, economic, financial, technological, and transportation center. Phoenix is located on the banks of what is now the normally dry Salt River (with the exception of Tempe Town Lake). The city was incorporated on February 25, 1881. The city is also known by its nickname, The Valley of the Sun or The Valley, because the city is surrounded by mountains on all sides. Residents of the city are known as Phoenicians.

The city is currently the fifth largest city in the United States in terms of population with a 2007 estimated population of 1,552,259. During the 1990s Phoenix competed for the title of fifth largest city in the United Stated with Philadelphia. Its city proper is the tenth largest for land area in the United States at 517 square miles (1,340 km²), causing this to result in a lower population density. As of 2007, the Phoenix Metropolitan Statistical Area (MSA) was the thirteenth largest in the United States, with an estimated population of 4,179,427.