POPULATION

As of February 2009, the United States has a total resident population of 306 million. It is a very urbanized nation, with 81% of the population residing in cities and suburbs as of mid-2005 (the worldwide urban rate was 49%). The mean population center of the United States has consistently shifted westward and southward, with California and Texas currently the most populous states.The total fertility rate in the United States estimated for 2008 is 2.1 children per woman, which is roughly the replacement level.However, U.S. population growth is among the highest in industrialized countries,since the vast majority of these have below-replacement fertility rates and the U.S. has stronger immigration. Accordingly, the United States Census Bureau shows an increase of 0.95% between November 2007 and November 2008 for the resident population. Nonetheless, though high by industrialized country standards, this is below the world average annual rate of 1.19%.Long term, the U.S. growth rate is projected to surpass that of the world at large: the Census Bureau projects a population of 439 million in 2050, which is a 46% gain from 2007, compared to the world population's gain of 38% over the same period, per United Nations projections; per the U.N., the U.S. increase will be 32%, from 306 million in 2007 to 402 million in 2050.

People under 20 years of age make up over a quarter of the U.S. population (27.6%), and people age 65 and over made up one-eighth (12.6%) in 2007. The national median age was 36.7 years.


Source: http://www.mapsofworld.com/usa/thematic-maps/usa-population-map.html