This Is America's Fastest-Growing County

Based on the 2020 U.S. Census data, America grew more slowly in the past decade than at any time in over half a century. Over the 10 years since the 2010 figures were posted, the rise barely topped 7%. An aging population and decisions by many Americans to delay marriage contributed to the most modest increase to 331,449,281.

The increase varied substantially among America’s slightly more than 3,000 counties. In Alexander County, Illinois, the population dropped 36.4% to 5,240. The Wall Street Journal gave a partial reason, based on the figures from one town in Alexander County:

Cairo (pronounced KAY-ro) has been the epicenter of the county’s loss. A once bustling river port, the town has suffered for decades from the decline of shipping, coal mining, government and manufacturing jobs.

At the far end of the spectrum, the population in one county more than doubled from 2010 to 2020. The number of residents of McKenzie County, North Dakota, grew by 131.2% to 14,704. The county sits on the far western border of the state, where it meets Montana. Its county seat, Watford City, posted a much faster growth, from 1,744 in 2010 to 7,944 last year.

The growth of the county results largely from the huge fracking boom in the Bakken oil field. Oil produced by pressurized liquids forced into rock formations helped the United States get a measure of energy independence. This production peaked in late 2019. High-paying jobs in the industry drew tens of thousands of people.

The median household income in McKenzie County is unusually high. At $77,845, it sits about $10,000 above the comparable national number.

The second-fastest-growing county in America over the period also is in North Dakota. Williams County posted a growth rate of 82.8% to 40,950. It is immediately north of McKenzie County, and the reason for its growth is the same. The median household income in Williams County is an unusually high $87,161.

Will the growth of these counties continue over the next decade? Almost certainly not. While the fracking boom has not ended entirely, the industry has taken a downturn, driven by a drop in the price of crude.

These are the 20 fastest-growing counties in America:

County 2020 Population % Change
McKenzie County, N.D. 14,704 131.20%
Williams County, N.D. 40,950 82.80%
Hays County, Texas 241,067 53.40%
Dallas County, Iowa 99,678 50.70%
Comal County, Texas 161,501 48.90%
Bryan County, Ga. 44,738 48.00%
Wasatch County, Utah 34,788 47.80%
Trousdale County, Tenn. 11,615 47.60%
Lincoln County, S.D. 65,161 45.40%
Osceola County, Fla. 388,656 44.70%
Williamson County, Texas 609,017 44.10%
St. Johns County, Fla. 273,425 43.90%
Forsyth County, Ga. 251,283 43.20%
Madison County, Idaho 52,913 41.00%
Kaufman County, Texas 145,310 40.60%
Fort Bend County, Texas 822,779 40.60%
Nantucket County, Mass. 14,255 40.10%
Stark County, N.D. 33,646 39.00%
Sumter County, Fla. 129,752 38.90%
Rockwall County, Texas 107,819 37.60%

Click here to read about the fastest-growing city in America.