Puerto Rico's population was estimated at 3,885,877 in mid-2003, up from 3,528,000 in 1990. With a population density of 1,025 per sq mi (465 per sq km), Puerto Rico is one of the most densely populated areas of the world.
In 2003, there were 93 Puerto Rican males for every 100 females. That year, about 22.9% of the population was under 15 years of age, 65.2% were 15–64 years of age, and 11.9% were 65 years or over. The birthrate declined steadily from 38.9 live births per 1,000 population in 1950 to 18.2 in 1991 to 15 by 2003. The death rate, on the other hand, was 7.4 per 1,000 population in 1990 and 7.68 per 1,000 population in 2003.
The population was estimated to be 75.2% urban and 24.8% rural in 2000. San Juan is Puerto Rico's capital and largest city, with an estimated 2002 population of 433,412, followed by Bayamon, 224,670; Carolina, 187,468; Ponce, 186,112; and Caguas, 141,693.