The COVID-19 pandemic reshaped U.S. migration patterns, but not always in ways suggested by popular narratives. A Social Explorer analysis of counties with more than 50,000 residents shows that from 2020 to 2023, larger counties collectively gained 11.8 million people, while smaller ones lost about 150,000. Growth among the fastest growing counties in the US was less concentrated in high-profile boomtowns like Miami, Denver, or Boise than in suburban areas across the country.
Some of the fastest growth occurred in places with affordable housing and available land, such as Madison County, Idaho (+34.9%), Kaufman County, Texas (+23.8%), and Bastrop and Comal counties in Texas (near Austin and San Antonio). Suburbs of Dallas, Houston, Phoenix, and Orlando also surged, with Collin County, Texas, gaining the most new residents numerically (+110,563). By contrast, expensive coastal metros and struggling rural counties often lost residents.
Los Angeles County saw the largest numerical decline (–192,276), followed by San Diego and San Francisco, with Washington, D.C., and Baltimore also shrinking. High housing costs, remote work flexibility, lower immigration, and slowing birth rates contributed to these declines. Ultimately, the post-COVID era highlighted a major demographic shift: suburban and exurban counties emerged as the biggest population winners, while urban cores and rural regions were more likely to lose residents.
Understanding Post-COVID Migration Patterns
Conventional wisdom holds that a combination of post-COVID factors – high mortgage interest rates, the growth of work-from-home positions, and increased political polarization led to an influx of new residents in places like south Florida, Austin, and the Rocky Mountains. However, it may have been premature.
A Social Explorer analysis finds that geographic mobility in the wake of the COVID-19 pandemic has been much more nuanced among U.S. counties with more than 50,000 people. The population in the larger areas grew by almost 11.8 million people between 2020 and 2023, while places with fewer than 50,000 residents lost 150,000 people.
And contrary to conventional wisdom, most of the newcomers didn't settle in cities like Miami, Denver, or Bozeman, Mont. While some of the greatest percentage growth occurred in the suburbs of Austin, Dallas, Jacksonville, and Orlando, the population increases were distributed throughout the nation, especially in suburbs adjacent to major metro areas.
The Fastest Growing Counties in the US by Percentage
Although Boise, Idaho, attracted attention as a COVID-era boomtown, Ada County only added 8.2 percent to its population, growing to include a little more than 508,000 people. Meanwhile, Madison County, Idaho emerged as the fastest growing county in the US during the four-year period, adding 34.9 percent to its population while swelling to include more than 53,500 people. The Rexburg area, which has a large number of Church of Jesus Christ of the Latter-Day Saints followers, has been known as a relatively affordable region that offers quick access to Grand Teton and Yosemite national parks.
Kaufman County, Texas was the second fastest-growing area in the nation among large counties. This Dallas exurb added 23.8 percent to its population, growing to 160,700 people. The county, located southeast of the Dallas-Fort Worth metropolitan statistical area (MSA), was the fastest-growing suburb in the area largely because of its relatively small population and cheap land that attracted homebuyers from more expensive parts of the nation.
While Austin was considered one of the major post-COVID population gainers, the area between Austin and San Antonio far surpassed growth in Travis County, the Texas capital. Bastrop County, located just southeast of Austin, saw its population soar 17.9 percent between 2020 and 2023, rising to almost 102,400 people. And less than 80 miles southwest of Austin, the San Antonio suburb of Comal County registered a 17.2 percent population gain to grow to 174,500 people.
Nye County, Nevada was the fifth fastest-growing large county in the United States during the post-COVID period, recording a 16.9 percent population gain to grow to 53,207 people. Growth in the exurb of Pahrump was spurred by relatively inexpensive and available land and soaring home prices in the Las Vegas area.
The sixth through tenth fastest-growing large counties in the post-COVID U.S. were:
- Lincoln County, South Dakota (Sioux Falls), +16 percent to 68,286
- Rockwall County, Texas (Dallas), +15.6 percent to 116,931
- Dallas County, Iowa (Des Moines), +15.2 percent to 104,136
- Hays County, Texas (Austin), +15.1 percent to 256,429
- Jackson County, Georgia (Atlanta), +14.4 percent to 80,640
Fastest Growing Counties by Population Numbers
Among the 10 counties with the largest numerical changes, half could be considered distinct suburbs. Collin County, Texas, an exurb north of Dallas, gained more people between 2020 and 2023 than any other U.S. county, adding 110,563 people, or 11 percent, to grow to 1.1 million people. Denton County, Collin County's western neighbor, was No. 2, adding 9.7 percent and growing by 83,954 people for a total of 945,644 residents.
Maricopa County, Arizona (Phoenix), was the third-biggest grower during the COVID era, adding 79,208 people (1.8 percent) to boost its population to 4.5 million. Harris County, Texas (Houston) was fourth, adding 77,970 people (1.7 percent) to increase its population to 4.8 million. Maricopa, Harris, Kings County, N.Y. (Brooklyn); Orange County, Fla. (Orlando); and Clark County, Nev. (Las Vegas), were the only core urban areas to rank among the 10 largest-growing counties between 2020 and 2023.
Other counties in the top 10 included:
- Williamson County, Texas (Austin), +12.9 percent to 643,889
- Kings County, New York, +2.7 percent to 2.6 million
- Fort Bend County, Texas (Houston), +8.7 percent to 859,721
- Orange County, Florida, +4.9 percent to 1.4 million
- Clark County, Nevada, +2.9 percent to 2.3 million
- Montgomery County, Texas (Houston), +10.9 percent to 654,722
Counties with the Largest Population Declines
Not all counties with more than 50,000 people gained population; indeed, the counties that lost the most residents over the four-year period tended to be on the smaller side. Robeson County, North Carolina suffered the greatest population decline between 2020 and 2023, with its population plunging 11.2 percent, down 14,798 people to 116,858. The largest county by size in the state, Robeson has a large agricultural economy. The county is located just south of Fayetteville on the South Carolina border, and reports the highest crime rates in the state.
Neighboring Columbus County, North Carolina recorded the second-greatest percentage decline in population among larger counties, with its population losing 5,206, or 9.4 percent, to 50,453 residents. Like Robeson, Columbus is a largely rural county with agricultural and manufacturing sectors that have fallen on hard times.
Apache County, Arizona, a thin slice of land that runs along the New Mexico border to the Four Corners, suffered the third-greatest percentage decline in population. It lost 8.4 percent of residents, about 6,034 people, to fall to a total population of 65,680. The county includes parts of the Navajo Nation, Fort Apache Indian Reservation, and Zuni Indian Reservation.
A slow birth rate, increased out-migration to other states, and decreased foreign immigration that were registered statewide contributed to an 8.4 percent population decline in Isabella County, Michigan. The central Michigan county lost 5,888 people between 2020 and 2023 to wind up with 64,475 residents.
Similar circumstances caused a decline in the population of Jackson County, Illinois. The county, located on the Missouri border in southern Illinois, registered a four-year decline of 4,811 people, an 8.4 percent loss. The county, which is home to Southern Illinois University, has a population of 52,706.
Other big losers from a percentage standpoint included:
- Acadia Parish, Louisiana, -8.3 percent to 57,218
- Athens County, Ohio, -6.6 percent to 61,573
- Sampson County, North Carolina, -6.4 percent to 59,245
- Butte County, California, -6.2 percent to 209,470
- Darlington County, South Carolina, -6.1 percent to 62,754
Major Metropolitan Areas Show Significant Population Losses
Mid-sized, rural counties were the biggest losers on a percentage basis in a post-COVID world. It stands to reason that large, urban counties would be the biggest losers on a numerical basis since they have larger populations. To a certain extent, that's true – but many of the biggest losers weren't necessarily obvious, although the three largest declines (and half of the top 10) were registered in California.
Los Angeles County was the biggest loser from a numerical standpoint, losing 192,276 people, or 1.9 percent of its population, and falling below 10 million people. San Diego County was second, losing 41,188 people, or 1.2 percent of its population, to drop to 3.3 million people. San Francisco, where pundits warned that a "doom spiral" of population loss was in danger of occurring, ranked third, losing 4.4 percent of its population, or 38,463 people to end 2023 with 836,321 residents.
The three California counties suffered large population losses for a number of reasons, with the most common being the ability of more people to work outside of a fixed office. However, a decline in immigration, falling birth rates, and outmigration caused by high costs of living and natural disasters also played a role in the losses.
The nation's capital ranked fourth for numerical population loss. Washington, D.C., reported a decline of 29,895 people, a 4.3 percent population loss over the four-year period. It was followed by Baltimore city, Maryland, which lost 25,081 people, or 4.2 percent of its residents.
Washington, which saw its population fall below 700,000 people, was another victim of the remote work phenomena, fueled heavily by the large number of federal workers who didn't require an office to do their jobs. Meanwhile Baltimore, separated by only 40 miles of interstate from Washington, suffered from a different set of circumstances that included limited economic opportunities, high crime, and continued outmigration, especially to nearby Howard and Montgomery counties.
Other counties that lost a significant number of residents included:
- Milwaukee County, Wisconsin, -2.3 percent to 927,656
- Santa Clara County, California, -1.1 percent to 1.9 million
- San Mateo County, California, - 2.7 percent to 745,100
- Miami-Dade County, Florida, -0.7 percent to 2.7 million
- Suffolk County, Massachusetts, -2.4 percent to 782,172
It's worth noting another caveat to COVID-era population shifts. While Miami was widely seen as the beneficiary of a New York metro exodus – especially early in the pandemic – it ultimately lost population between 2020 and 2023, primarily due to high costs of living and limited job opportunities for low- and middle-income workers.
Key Takeaways: The Fastest Growing Counties in the US
A retrospective demographic analysis of population trends during the COVID-19 pandemic era, circa 2020-23, finds that conventional wisdom often relied on premature results. Major metro areas such as San Francisco, New York, and Washington, D.C., did lose residents as a greater share of the labor force gained the ability to work remotely. Population gains in other areas such as Miami and Austin, however, were overstated, with most of the new residents settling in suburban areas with lower costs of living rather than moving to more expensive core urban areas.
The fastest growing counties in the US during this period were predominantly suburban and exurban areas that offered affordable housing, available land, and proximity to major metropolitan centers. This trend represents a significant demographic shift that continues to reshape America's population distribution.
For detailed analyses of the COVID-era population changes – from state- to neighborhood-level data – we recommend Social Explorer's customizable, easy-to-use, award-winning demographic mapping software.