Census data reveals which American counties saw the decade's biggest growth

Your 2010 U.S. Census Bureau forms are filled out and mailed back by now -- right? The April 1 deadline has come and gone.

It will take months, even years, however, for the decennial data to be sifted, analyzed and acted upon -- having an impact on congressional representation and other important outcomes determined by the information.

Demographers are getting a glimpse of one piece of the puzzle already, however: which U.S. counties had the biggest population growth over the last 10 years, based on recently released Census population estimates for the last decade and a Forbes.com analysis of those estimates. The results are based on net domestic migration, net immigration and new births. The number of people moving out of counties between 2000 and 2008 was subtracted from the number of newcomers.

Despite the resurgence of some urban areas, like downtown Los Angeles, where young professionals seeking culture and night life accessible by foot bought lofts and condos, it is suburban areas that got the big boost, according to the new data. Kendall County outside of Chicago, Il; Pinal County near Phoenix, Ariz.; and Forsyth County near Atlanta, Ga., for example, saw rapid growth (internal migrants made up 39%, 37% and 33% of the population, respectively). That's because the first half of the decade saw a spike in government and education jobs in those locations, and big corporations, such as Coca-Cola and Walmart, boosted their payrolls too. Affluent Americans flocked to Dallas suburbs, which saw a high number -- 30% to 40% -- of in-migration.