Census Bureau: U.S. Gains Up to 31 Million More Residents

The U.S. population grew 8.6% to 11% over the last decade to a total of between 305.7 million and 312.7 million residents this year, the U.S. Census Bureau reported Monday. That's up from 281.4 million people in 2000.

In its demographic analysis -- which is based on data that's independent from the regular 2010 Census, such as birth and death records, international migration statistics and Medicare enrollment -- the bureau also concluded that women outnumber men to about 1.8 million, and that the largest age contingent is between 45 and 50 years old.

The bureau says it decided to provide a population range -- instead of a single number -- to reflect the challenges of tracking domestic residents amid increasing immigration. "For the first time, we are providing a series of demographic analysis estimates to more clearly demonstrate the uncertainty in these figures," U.S. Census Bureau Director Robert Groves said in a statement.