The results of the 2010 U.S. Census, released Tuesday, show the state of Texas added 4.3 million residents over the last decade. (Associated Press)

The United States Census Bureau says the country's population is 308,745, 538, reflecting the lowest growth during a single decade since the Great Depression.

Census Bureau director Robert Groves says the figure for the 2010 census, released Tuesday, represents an increase of 9.7 per cent over the 2000 U.S. resident population of 281.4 million. By comparison, the population grew by 13.2 per cent from 1990 to 2000.

California is the most populous state with 37.2 million residents. Wyoming is the least populous with 563,626 residents.

Since the 2000 census, Texas gained the most people, up 4.3 million residents to 25.1 million. Nevada gained the most residents as a percentage of its 2000 census count, growing 35.1 per cent to 2,700,551.

The South and the West showed the strongest growth, although the Northeast and the Midwest also grew.

The new numbers are a boon for Republicans, with Texas leading the way among Republican-leaning states that will gain House of Representatives seats at the Northeast's expense.

Texas gained four House seats and Florida picked up two as a result of the new census count, while New York and Ohio each lost two seats.

Following each once-a-decade census, the U.S. must reapportion the House's 435 districts to make them roughly equal in population, with each state guaranteed at least one seat.