8 Fastest-Growing U.S. Counties

June 20, 2011

The U.S. population is projected to increase by 8.9 percent — or 27.7 million people — from 2010 to 2020, according to ProximityOne, a demographic resource firm.

So which counties are expected to get the biggest population boosts by 2020? According to ProximityOne data, the following are the counties with the highest projected percentage change from 2010 to 2020.

1. St. Bernard Parish, La
2010 population: 36,753
2010 population: 74, 470
Percent change: 102.62

2. Bent County, Colo.
2010 population: 6,614
2020 population: 11,330
Percent change: 71.30

3. Orleans Parish, La.
2010 population: 348,899
2020 population: 570,109
Percent change: 63.40

4. Filpin County, Colo.
2010 population: 5,519
2020 population: 8,624
Percent change: 56.26

5. Franklin County, Wash.
2010 population: 79,210
2020 population: 123,352
Percent change: 55.73

6. Duchesne County, Utah
2010 population: 18,853
2020 population: 29,148
Percent change: 54.61

7. Eureka County, Nev.
2010 population: 2,012
2020 population: 3,079
Percent change: 52.88

8. Sublette County, Wyoming
2010 population: 10,367
2020 population: 15,760
Percent change: 52.02

Meanwhile, several counties are expected to lose some of its population within the next decade. The counties that are projected to lose the most in population are Bristol Bay Borough, Alaska (which stands to lose 61.94 percent of its population), Grant County, Neb. (-56.79 percent), and Cameron Parish, La. (-54.16 percent).

Find the 2010 to 2020 projection for your county.

Source: “Demographic Trends 2000-2020,”Proximity (June 16, 2011)