The population of Colombia in 2003 was estimated by the United Nations at 44,222,000, which placed it as number 27 in population among the 193 nations of the world. It is the third most populous country in Latin America, following Brazil and Mexico. In 2003 approximately 5% of the population was over 65 years of age, with another 33% of the population under 15 years of age. There were 98 males for every 100 females in the country in 2003. According to the UN, the annual population growth rate for 2000–2005 is 1.59%, with the projected population for the year 2015 at 52,190,000. The population density in 2002 was 39 per sq km (100 per sq mi), with about 95% of the population residing in the mountainous western half of the country.
A rapid transfer of population to urban centers has taken place since the 1950s; it was estimated by the Population Reference Bureau that 74% of the population lived in urban areas in 2001. The capital city, Bogota, had a population of 6,158,000 in that year. The populations of other major metropolitan areas were as follows: Medellín, 3,831,000; Cali, 2,082,000; and Barranquilla, 1,246,000. Other metropolitan areas include Cartagena, Bucaramanga, and Cúcuta. According to the United Nations, the urban population growth rate for 2000–2005 was 2.2%.