Reflecting a decades-long trend of population migration from the Northeast to the Sun Belt, the vast majority of the 100 fastest-growing counties in the United States fall below the Mason-Dixon Line. Eighteen of the top 100 are in Texas, another 14 are in Georgia, and 11 more are in Virginia. Not a single one of the fastest-growing counties is in the Northeast, and only five—one each in West Virginia, Indiana, and Iowa, and two in Kentucky—are in the Rust Belt.
Rapid growth helped Obama put new states into play. Obama performed better than the average Democratic presidential nominee from 1976 to 1992 in each of the 11 counties in Virginia that made the list, by an average of 16 points. (He did best in Falls Church city, where he outperformed his predecessors by 21 points, and he even improved upon traditional Democratic performance in King George County, east of Fredericksburg, by a single point.) Obama ran up big margins in the two North Carolina counties to make the list—Mecklenburg and Wake—improving by double digits on the results for earlier Democratic nominees.
All told, Obama outperformed his predecessors by more than 10 points in 21 of the 100 fastest-growing counties, while McCain beat earlier Republican nominees by 10 points in 20 of the fastest-growing counties. Obama's better performances came in swing states and in heavily Republican territory like Summit County, Utah; Hamilton County, Ind.; and Shannon County, S.D. McCain’s best improvements came almost exclusively in red states; he improved noticeably in just one county (in a state that he lost)—Sumter County in Florida, where his score was 14 points better than the average Republican.
McCain did best in the counties with the highest growth rate. He won both counties—Charlton in Georgia and St. Bernard Parish in Louisiana—that grew by more than 10 percent over the past year, and he won 11 of the 15 fastest-growing counties. The smaller the county, the better chance McCain won there: He won 23 of the 34 rapidly growing counties that had fewer than 50,000 people.
Obama, on the other hand, performed best in the counties that were large to begin with. Obama’s 200,000-vote margin over McCain in the 100 fastest-growing counties was entirely provided by big margins in Hillsborough County, Fla. (Tampa); Travis County, Texas (Austin); Fulton County, Ga. (Atlanta); and Mecklenburg County, N.C. (Charlotte). Obama won the five largest counties on the fast-growth list, all of which have populations greater than 900,000, and nine of the top 12 largest fast-expanding counties.
Growth and the Vote
Four years ago, President Obama narrowly won the popular vote, 51 to 48 percent, in the 100 fastest-growing counties. Although he only won about a third of those 100 counties, those that Obama carried tended to be the most populous.
Fastest-growing counties from April 2010 to July 2011, by 2008 presidential winner
Graphic by PETER BELL
Sources: Census Bureau, state elections officials
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