Flagler County, Fla., was the fastest growing county between April 1, 2000, and July 1, 2009, according to the most recent population estimates for each of the nation's 3,143 counties released by the U.S. Census Bureau on June 10. The estimates, which are broken down according to by race, Hispanic origin, age and sex, are the last to use the 2000 Census results as a base, according to the Census Bureau.

Flagler County saw a 101.9 percent increase in the number of housing units in the county during the nine years covered by the estimates. The county started with 24,452 in April 2000 and ended with 49,373 by July 2009, according to a list of the 100 fastest-growing counties that accompanies the new estimates. The last county on the list, Louisa County, Va., saw a 35 percent increase in housing units during the time period.

The estimates were updated by using administrative records to estimate components of population change, such as births, deaths, and domestic and international migration. The 2011 population estimates will be the first in the estimates series to be based on the 2010 Census population counts, which are due to be released in December.

The 2010 Census state population totals will be used to apportion seats in the U.S. House of Representatives. By April 1, 2011, the Census Bureau must release race and Hispanic origin counts for counties, cities and smaller geographic areas so that states can proceed with redistricting. "Census numbers govern the distribution of more than $400 billion in federal funds each year and serve as the baseline for future post-census population estimates," Census Bureau Director Robert Groves said in a statement. "The census provides a clear and detailed picture of our communities, including their changing demographic characteristics."

The Census Bureau also released July 1, 2009, population estimates by age and sex for Puerto Rico municipios. Annual estimates for the 2000 to 2009 period are provided.

Download the latest Census county population estimates and the complete list of the 100 fastest growing counties.

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