The US population stood at 308.7 million this year, up 9.7 per cent from 10 years ago in the slowest growth since the 1930s, the Census Bureau said in long-awaited findings.

The Census Bureau put the US population at 308,745,538 as of last April 1, with a steady shift towards southern states such as Arizona, Nevada and Texas.

The growth in the world’s largest economy was the slowest since the 1930s, when the population expanded by only 7.3 per cent.

The latest figure “is thus the second lowest of the past century,” census chief Robert Groves told a news conference announcing the results.

The census, which is mandated by the US Constitution, is used to apportion the 435 seats in the House of Representatives – and, by correlation, each state’s power in electing the President.

Texas, where the Republican Party dominates, picked up four seats to have 36 in the House – second only to California, which stayed steady at 53 states.

Other states that gained seats included Arizona, Florida, Georgia, Nevada Utah and – almost alone among states that solidly support President Barack Obama’s Democratic party – Washington state.

States that lost seats included Michigan, New York, Ohio and Pennsylvania, which have been hard hit by the economic downturn.