High Quality Content by WIKIPEDIA articles! As of 2006, Arizona had an estimated population of 6,166,318, which is an increase of 213,311, or 3.6%, from the prior year and an increase of 1,035,686, or 20.2%, since the year 2000. This includes a natural increase since the last census of 297,928 people (that is 564,062 births minus 266,134 deaths) and an increase due to net migration of 745,944 people into the state. Immigration from outside the United States resulted in a net increase of 204,661 people, and migration within the country produced a net increase of 541,283 people. New population figures for the year ending July 1, 2006, indicate that Arizona is the fastest growing state in the United States, with 3.6% population growth since 2005, exceeding the growth of the previous leader, Nevada.