• Half of the 50 fastest-growing micro areas between 2011 and 2012 were in the South, 14 in the West, 10 in the Midwest and one in the Northeast.
• The most populous micro area was Claremont-Lebanon, N.H.-Vt., with a 2012 population of 217,000. Hilo, Hawaii, was second.
• Chattahoochee, Ga., home to Fort Benning, was the nation's fastest-growing county of 10,000 or more residents as its population climbed 10.1 percent, between July 1, 2011, and July 1, 2012.
• Los Angeles was the nation's most populous county on July 1, 2012, with nearly 10 million residents, followed by Cook, Ill. (Chicago); Harris, Texas (Houston); Maricopa, Ariz. (Phoenix); and San Diego, Calif.
• Texas had 11 counties among the 50 fastest-growing, as well as 11 among the 50 highest numeric gainers.
• The county with the fastest decline in population was Bradford, Fla., at 5 percent. Another Florida county (Hendry) was second, followed by a pair of counties in Alabama (Macon and Perry).