Other census findings:
—The 65-and-older population grew 4.3 percent between 2011 and 2012, to 43.1 million, or 13.7 percent of the U.S. population.
—Florida had the highest share of residents 65 and older, at 18.2 percent, followed by Maine and West Virginia. Alaska had the lowest share of older residents, at 8.5 percent, followed by Utah and Texas. By county, Florida's Sumter County was tops in the share of the 65-plus age group, at 49.3 percent.
—The 85-and-older population increased by about 3 percent from 2011 to 2012, to almost 5.9 million. The number of centenarians rose to almost 62,000.
—The nation's median age rose to 37.5, up from 37.3 in 2011.
Dreier reported from Las Vegas.