WASHINGTON (RNN) - The U.S. population grew at the second slowest rate since the Great Depression, with just a 9.7 percent increase over the past 10 years.
U.S. Census Bureau Director Robert Groves said Tuesday the U.S. population is now more than 300 million, with 308,745,538 people calling the U.S. home in April 2010. In April 2000, the population was about 281.5 million.
During the Depression, the population increased 7.3 percent.
The census numbers are used to apportion the states' representation in the House of Representatives. Each state receives at least one seat, with the remaining 385 seats divided according to each state's population.
The census counted every resident living in the U.S. - whether they were documented or not - a method that has continued since the first census in 1790. The census did not include a question about citizenship.
The South and the West reported the largest gains in population, at 14.3 percent and 13.8 percent respectively. The region with the smallest growth is New England with 3.2 percent.
The state with the largest growth in population was Nevada at 35.1 percent. That's a decrease over a decade ago, when it experienced a growth of 66 percent.
The state with the lowest growth in population was Michigan at 0.6 percent.
The state with the largest growth in the Northeast was New Hampshire, with a growth of over six percent.
In the South, Texas led the way with 20.6 percent growth over Louisiana, which had only 1.4 percent growth.
And in the West, Nevada's 35.1 percent growth contrasted with Montana's 9.6 percent growth.
These numbers are very important, because they affect the distribution of seats in the U.S. House of Representatives.
Reapportionment of seats in the lower chamber of Congress is the constitutional purpose of the census.
"Representatives shall be apportioned among the several states according to their respective numbers," the nation's founding fathers wrote.
Each state receives at least one seat, and the remaining 385 seats are divided based on the populations of the states.
"This method is based on the population on the population of the 50 states, excluding the District of Columbia, supplemented by the affiliated overseas populations," Groves said.
Starting next year, there will be a shift of 12 seats in the House - a change that will affect 18 states.
Arizona, Florida, Georgia, North Carolina, Texas, Utah and Washington will all gain seats.
With a gain of four seats, Texas will take one-third of the new positions in Congress.
New York and Ohio, two states that helped Barack Obama secure the presidency in 2008, both lost seats.
The gains in red states will greatly benefit the Republican party, as only one of the states receiving new seats has a Democratic governor.
With the adjustment in population, each representative will now represent 710,767 U.S. citizens, up 646,952 in 2000. The original members of the House represented just 34,000 people per person.
"We have grown," Groves said.
The most populous states are, in order, California, Texas, New York, Florida, and Illinois.
New York is the only state that has ranked among the five largest in each decade since 1970.
New Jersey, one of the original 13 states in the 1790 census, has the largest population density, and Alaska has the lowest.
In 2009, the 2010 census was ranked as one of the federal programs most likely to fail.
But the Commerce Department was happy to announce that it completed the 2010 census on time and under budget.
The department was given $7.4 billion for its 2010 census budget, and it returned $1.87 billion to the U.S. Treasury, shaving a quarter of its budget, said Commerce Secretary Gary Locke.
Locke gave credit to the budget cut to the American people, 74 percent of whom returned their census forms by mail, which allowed the Commerce Department to hire less door-to-door employees.
Still, the hired 1.2 million people across the nation, including thousands of part-time workers, something that was good news for Americans in the wake of a struggling economy.
The first U.S. census was taken in 1790 and managed by Thomas Jefferson.
U.S. marshals took 18 months to conducted counts in the original 13 states.
The original census asked ten questions, four less than the 2010 census.
2010 marked only the 23rd time a national census was taken.
From the U.S. Census Bureau: