Official Portrait of Barack Obama

As of May 14, 2012, the United States has a total resident population of 313,544,041, making it the third most populous country in the world. It is a very urbanized population, with 82% residing in cities and suburbs as of 2008 (the worldwide urban rate is 50.5%). This leaves vast expanses of the country nearly uninhabited. California and Texas are the most populous states, as the mean center of United States population has consistently shifted westward and southward. New York City is the most populous city in the United States.

The total fertility rate in the United States estimated for 2009 is 2.01 children per woman, which is below the replacement fertility rate of approximately 2.1. 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 higher levels of immigration. The United States Census Bureau shows population increase of 0.91% for the twelve-month periods ending in July 2011. Nonetheless, though high by industrialized country standards, this is below the world average annual rate of 1.092%.

There were 155.6 million females in the United States in 2009. The number of males was 151.4 million. At age 85 and older, there were more than twice as many women as men. People under 20 years of age made up over a quarter of the U.S. population (27.3%), and people age 65 and over made up one-eighth (12.8%) in 2009. The national median age was 36.8 years. Racially, the U.S. has a White American majority.