Following a dramatic population decline following Hurricane Katrina, two New Orleans-area parishes were the fastest growing counties in the U.S. from 2006 to 2007. St. Bernard Parish, America's fastest-losing county from 2005 to 2006 — grew by a whopping 42.9% between July 1, 2006, and July 1, 2007 (an increase of almost 6000 people). The population of Orleans Parish rose by 13.8 percent, or nearly 29,000. The rest of the top ten counties in percentage growth are in the Sunbelt except one in Illinois.

As for numerical growth, Maricopa County, Arizona (the location of Phoenix), grew by 102,000 people between 2006 and 2007. All of the top ten numerical growth counties are also in the South and West including five in Texas. See the U.S. Census Bureau's press release for more details.