Maricopa County, Arizona

Maricopa County is in central Arizona and includes the greater part of the Phoenix metroplex. Maricopa County contains 9,203 square miles of land and 21 square miles of water. Maricopa County is the 4th most populous county in the United States. There are 12 Indian Reservations in the county. The county seat is Phoenix.

Update, 2009: For the first time since Europeans began settling in the area, Maricopa County appears to be losing population as a direct result of the global financial crisis, a crisis brought about by many of the very bankers, developers, investment advisers and mortgage brokers who call Maricopa County "home." Foreclosures are rampant as the local economy contracts. It also doesn't help matters that many of the local jobs in the large financial institutions that used to run major operations in Phoenix have shifted large portions of their business overseas (that move often paid for with money derived from the taxpayer's bailout of those same institutions).

Update, 2012: It's estimated that the population of Maricopa County has dropped by more than 200,000 since 2009.

A Landsat image of the Phoenix Metro area