Based on national Census 2000 results, Arizona's total population is the second fastest growing in the United States, and is expected to maintain that position through 2030.

How Does Arizona Rank in Populous?
  Among the 50 states and District of Columbia, Arizona's percentage of population gain from 1990 to 2000 is approximately 40 percent, and has grown approximately 14 percent from 2000 to 2005.

Population Growth Projection from Federal Census Data
    Arizona had a population of 5.13 million people in 2000. The state ranked as the 20th most populous that year. By 2015, Arizona is projected to be the 13th most populous state with 7.5 million people and by 2030 it is projected to be the 10th most populous with 10.7 million people.

  Following is the Arizona population growth projection from 2000 through 2030 as developed by Federal Census Data.