USDA Economic Research Service
The number of people living in nonmetropolitan (nonmetro) counties now stands at 46.2 million–15 percent of U.S. residents spread across 72 percent of the land area of the U.S.*
http://www.ers.usda.gov/amber-waves/2013-may/nonmetro-areas-as-a-whole-experience-first-period-of-population-loss.aspx#.UZmh38pXrWa
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