Colorado ranked 22nd in population in the US with an estimated total of 4,506,542 in 2002, an increase of 4.8% since 2000. Between 1990 and 2000, Colorado's population grew from 3,294,394 to 4,301,261, an increase of 30.6%, the 3rd-largest percentage increase in the country for this period (exceeded only by Nevada and Arizona), and the 8th-largest gain in population size. The population is projected to reach 5.2 million by 2025.

Colorado rose from 30th in population in 1970 to 28th in 1980, and 26th in 1990, with a 14% increase during the 1980s. The population density in 2000 was 41.5 per sq mi. The estimated median age in 2000 was 34.3 years, 9.7% of the

population was over 65, and persons under 18 years old accounted for 25.6% of the population.

Denver is the state's largest city and was, in 2002, the 26th largest US city. Its estimated 2002 population was 560,415, but its metropolitan area (including Boulder and Greeley) exceeded 2,417,908 or more than half the state's population in 1999. Other major cities, with their estimated 2002 population figures, are Colorado Springs, 371,182; Aurora, 286,028; Lakewood, 143,754; Fort Collins, 124,665; Westminster, 103,599; and Pueblo, 103,411.