In 2002 the District of Columbia had a larger population than the last-ranked state of Wyoming, with an estimated 570,898, an decrease of 0.2% since 2000. Between 1990 and 2000, the District's population declined from 606,900 to 572,059, an decrease of 5.7%. The population is projected to reach 655,000 by 2025.
In 2000 the median age was 34.6. Persons under 18 years old accounted for 20.1% of the population while 12.2% were age 65 or older.
In 1990 the District of Columbia outranked three states in population, with a census total of 606,900, a decline of almost 5% from 1980. Considered as a city, the District ranked 23rd in the US in 2002. The population density in 2000 was 9,316.4 persons per sq mi, the 7th-highest of any city in the US (behind Philadelphia and ahead of Baltimore).
Even as the capital's population has declined, the number of Washington, D.C., metropolitan area residents has been increasing, from 3,040,000 in 1970 to 3,251,000 in 1980, to 3,924,000 in 1990, and to an estimated 4,739,999 in 1999. The District's population is 100% urban and extremely mobile.