3 Things to Know About Population Change Across America's Counties
The latest release of the U.S. Census Bureau's population estimates marks an important shift in the nation's post-pandemic demographic story. After several years of accelerating population growth, the pace slowed considerably in 2025, with the nation adding 1.78 million residents, just over half the increase recorded in 2024.1 The primary reason for this slowdown is clear: net international migration fell by 54% between 2024 and 2025, while natural increase, the difference between births and deaths, remained stable.2
International migration fueled the post-pandemic population rebound, then slowed sharply in 2025
U.S. population change by component (natural change and net international migration), 2021–2025
Natural increase remained relatively stable throughout the period, while international migration fueled the post-pandemic population rebound and largely explains the slowdown in 2025. Domestic migration sums to zero nationally and is excluded.
Source: NACo Analysis of U.S. Census Bureau, Population Estimates Program (PEP) - Vintage 2025 Population Estimates.
Population change, however, is not occurring uniformly across the country. While the nation experienced growth in 2025, those gains were concentrated in fewer counties. Migration patterns and changing age demographics are reshaping communities, influencing county planning, workforce development, housing and public services for the foreseeable future.
Here are three things county leaders should know from the latest Census population estimates.
Finding #1
Population growth became less widespread across U.S. counties in 2025
The share of counties gaining population fell to 34% in 2025 from 44% in 2024, while nearly half of all counties remained stable and 19% declined.
Dive deep
In 2025, 34% of counties experienced population growth greater than 0.5%, while nearly half (47%) remained stable (±0.5%) and 19% experienced population declines below −0.5%. The slowdown was also evident among counties that had recently been growing. Of the 1,336 counties that gained population between 2023 and 2024, more than 8 in 10 experienced slower growth in 2025, and 541 no longer met the population growth threshold, shifting into either the stable or declining category.
34%
of counties gained population in 2025
Down from 44% in 2024, the steepest single-year drop in the five-year window.
Fewer Counties Experienced Population Growth in 2025
Map showing counties experiencing population growth (>0.5%), stable population (±0.5%) and population decline (<−0.5%)
Population growth became less widespread in 2025, with counties experiencing growth increasingly concentrated in the South and parts of the Mountain West.
Classification: Growing counties experienced population growth greater than 0.5%; stable counties experienced population change between −0.5% and +0.5%; declining counties experienced population loss greater than 0.5%.
Where growth continued, it was increasingly concentrated in the South and parts of the Mountain West.
Texas accounted for 18 of the nation's 50 fastest-growing counties with populations of at least 20,000, followed by Florida with eight, Georgia with five and South Carolina with four. Among counties with populations of 20,000 or more, the fastest growing was Jasper County, S.C. (6.0%), followed by Waller County, Texas (5.7%), Kaufman County, Texas (5.7%) and Jackson County, Ga. (5.3%).3
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Finding #2
Migration shaped growth differently by county size and region
Domestic migration was the leading source of growth in 82% of growing counties and was especially dominant among small counties, while international migration played a significant role in large counties. Regionally, the South captured roughly two-thirds of all county-level population gains, while domestic out-migration constrained growth in the Northeast and West.
Dive deep
In 2025, domestic migration, the movement of people between counties and states within the nation, was the primary driver of population growth across U.S. counties.4 Among the 1,032 counties classified as growing in 2025, domestic migration was the leading source of growth in 82%, compared with 10% where international migration led and 8% where natural increase was the primary driver.5 In more than 500 growing counties, deaths outnumbered births, meaning migration was not only the leading source of growth but the only reason population increased.
82%
of growing counties were powered primarily by domestic migration in 2025
In more than 500 growing counties, migration was the only source of population growth.
A similar pattern emerged among counties classified as declining. Domestic out-migration was the primary driver in 61% of these counties, while natural decrease accounted for most of the remainder. International out-migration played only a limited role.6
But the story looks different depending on county size.
About county size categories
NACo classifies counties by population size as follows: small counties have fewer than 50,000 residents, medium-sized counties have between 50,000 and 500,000 residents and large counties have more than 500,000 residents.
Among small counties that gained population, domestic migration was the primary driver in 88% of these jurisdictions. Affordability helps explain this pattern, as residents increasingly relocate from higher-cost urban areas toward more affordable suburban, exurban and smaller communities.7 Since 2020, some of the nation's fastest population growth has occurred along the outer edges of major metropolitan areas.8
Among medium-sized counties, domestic migration was the primary driver in 82% of those that gained population, consistent with the national average. Collectively, medium-sized counties gained nearly 600,000 residents through domestic migration in 2025, more than any other county size tier, suggesting that these communities absorbed a substantial share of moves from larger urban counties.9
Large counties told a different story. International migration was the primary driver in 48% of growing large counties, compared with 31% where domestic migration led. Many of the nation's largest urban counties have experienced sustained domestic out-migration, making international migration increasingly important for offsetting those losses. Even though it slowed in 2025, international migration remained the main driver of population growth in urban counties; without it, urban counties as a group would have shrunk.10
County growth by size, 2025
27%
of small counties (under 50,000) grew in 2025
Among those that grew, domestic migration led, driven by affordability and the pull of exurban communities
48%
of medium-sized counties (50,000–500,000) grew in 2025
Among those that grew, domestic migration led, absorbing the largest share of domestic migrants nationally
44%
of large counties (500,000+) grew in 2025
Among those that grew, international migration led, as urban counties structurally depend on immigration to offset domestic out-migration
Share of counties that grew, and their primary growth driver among those that did, by county size, 2025.
Source: NACo Analysis of U.S. Census Bureau, Population Estimates Program (PEP) - Vintage 2025 Population Estimates.
Regional patterns reveal another layer of variation. The South remained the nation's fastest-growing region, accounting for approximately 67% of all county-level population gains and growing by 0.89%, more than double the rate of any other region.11 Both domestic (+365,000) and international migration (+585,000) contributed to the region's growth, with Texas, Florida and North Carolina recording the largest population gains.12 Although the South continued to lead the nation in population growth, its growth rate fell below 1% for the first time since 2021, reflecting the broader slowdown in national population growth.
~67%
of all county-level population gains in 2025 occurred in Southern counties
Texas accounted for the largest population gain of any state in 2025, adding nearly 391,000 residents, nearly twice the second-highest state (Florida, +197K).
The West added nearly 276,000 residents in 2025, driven largely by international migration (+246,000), despite losing nearly 168,000 residents to domestic out-migration. California drove much of that regional domestic loss, losing approximately 229,000 residents to other states. Excluding California, the rest of the West gained approximately 60,000 residents through domestic migration, led by Arizona (+31,000), Idaho (+20,000) and Nevada (+15,000).13
Domestic out-migration offset international gains in the Northeast and West in 2025
Components of population change by Census region, 2025
The South gained residents through both domestic and international migration, while domestic out-migration offset some of the gains from international migration in the Northeast and West. The Midwest recorded modest positive domestic migration for the first time this decade.
Source: NACo Analysis of U.S. Census Bureau, Population Estimates Program (PEP) - Vintage 2025 Population Estimates.
The Midwest stood apart, recording positive domestic migration for the first time this decade. The region gained nearly 232,000 residents overall, reflecting a broader easing of the domestic out-migration that characterized Midwest states during the pandemic years, as movement toward the South and Mountain West has slowed in the post-pandemic period.14
The Northeast recorded the smallest regional population increase, adding nearly 73,000 residents. Domestic out-migration resulted in a loss of nearly 179,000 residents, offsetting much of the region's gains from international migration and leaving the region growing, but only narrowly.15
Finding #3
Counties are aging and facing growing demographic pressures
Senior populations grew in 97% of counties, while youth populations declined in 69% and the working-age share declined in 93%. More than half of all counties experienced the "Triple Squeeze" of growing senior populations, shrinking youth populations and declining working-age populations.
Dive deep
Population growth tells only part of the story. Many counties nationwide are experiencing significant shifts in their age composition. Senior populations are growing, youth populations are shrinking and the share of working-age adults is declining, creating new challenges for county planning, workforce development and public service delivery.
The senior population (ages 65 and older) grew in 97% of U.S. counties between 2020 and 2025, making it the most consistent demographic trend in the data. Today, older adults account for at least one in five residents in more than two-thirds of counties, and at least one in four residents in roughly one-quarter of counties. In 137 counties, the senior population grew by 25% or more over the five-year period.16
At the same time, the youth population is contracting across much of the country. Between 2020 and 2025, the number of residents under age 18 declined by nearly 1.5 million, and 69% of counties saw their under-18 populations shrink over this period.17 A key driver is declining fertility: the U.S. fertility rate fell to an all-time low of 1.6 children per woman in 2024, continuing a decades-long decline.18 The pattern is most pronounced in the Northeast, where 90% of counties lost youth population, followed by the Midwest (79%) and the West (73%). The South is the notable exception: while 58% of Southern counties still experienced declines, it was the only region whose total under-18 population grew, adding more than 340,000 children even as the other three regions collectively lost nearly 1.9 million.
The age composition of America's counties is shifting
Share of population across U.S. counties by age group, 2020–2025
Older adults accounted for a growing share of the U.S. population between 2020 and 2025, rising from 16.9% to 18.9%, while the share of children under 18 declined from 22.3% to 21.1%. The share of adults ages 25 to 64 also declined modestly, while the young adult population remained relatively stable.
Source: NACo Analysis of U.S. Census Bureau, Population Estimates Program (PEP) - Vintage 2025 Population Estimates.
Key county-level demographic pressures, 2020–2025
97%
of counties saw their senior population (65+) grow
93%
of counties saw their working-age population share (25-64) decline
69%
of counties saw their youth population (under age 18) decline
54%
of counties experienced all three demographic pressures simultaneously
Looking specifically at changes in the number of residents in each age group, more than half of U.S. counties experienced three demographic pressures simultaneously: a growing senior population, a shrinking youth population and a declining working-age population. We refer to this convergence as the “Triple Squeeze.”
Source: NACo Analysis of U.S. Census Bureau, Population Estimates Program (PEP) - Vintage 2025 Population Estimates.
The working-age population (ages 25 to 64), the backbone of the labor force and local tax base, presents a similar challenge. Nationally, the 25-to-64 population grew modestly (1.5%) between 2020 and 2025, but this headline figure masks substantial county-level variation. The number of working-age adults declined in 67% of counties over this period. This widespread decline was concentrated in small counties, which lost working-age population in the aggregate (-2.3%), while medium-sized and large counties recorded modest aggregate gains (+2.1% and +1.9%, respectively), offsetting losses elsewhere.19
An even more telling measure is the working-age share of the population: in 93% of counties, adults ages 25 to 64 made up a smaller share of residents in 2025 than in 2020. Even among counties that added working-age residents, 81% still saw their share of working-age adults decline. The distinction matters for workforce planning: a county can add working-age adults in absolute terms while still facing a shrinking share of the workforce. The Midwest was the most affected region, with 99% of counties experiencing a decline in the share of working-age residents between 2020 and 2025.
Implications of changing age demographics for counties
Growing senior populations
Increasing demand for aging-in-place services, accessible transportation and health care access
Shrinking youth populations
Changing needs for schools, childcare and long-term workforce pipelines
Declining working-age populations
Pressures on workforce availability, service delivery capacity and the local tax base
Taken together, these shifts create overlapping demographic pressures for many counties. Looking specifically at changes in the number of residents in each age group, more than half (54%) of U.S. counties experienced the “Triple Squeeze” between 2020 and 2025: a growing senior population, a shrinking youth population and a declining working-age population. The pattern is most pronounced in the Northeast and Midwest, where 75% and 68% of counties, respectively, experienced all three conditions, compared with 42% of counties in the South.
What this means for counties
The 2025 population estimates show that population change across America's counties is becoming more uneven. While the nation's population continues to grow, that growth is slowing, fewer counties are gaining residents, and migration continues to shape where and how communities are growing.
At the same time, demographic shifts are reshaping the age composition of counties, which affects nearly every dimension of county governance. Counties with rapid senior growth face rising demand for health care access, transportation alternatives and aging-in-place services, even as their workforce and tax base may be contracting. Counties losing youth population face declining school enrollment, changing childcare needs and long-term workforce pipeline challenges. Counties experiencing the “Triple Squeeze” face several of these pressures simultaneously. Understanding not just how many people live in a county, but who they are and how that composition is changing, is essential for county leaders planning services, infrastructure and budgets for the decade ahead.
For county leaders, understanding population change means looking beyond whether a county is simply growing or shrinking. Understanding what is driving population change and how the population composition is shifting can help inform decisions about housing, workforce development, infrastructure and public services.
NACo will continue to surface timely research and data insights to help county leaders understand the trends shaping their communities and the implications for county government.
Data source and notes
This analysis is based on the U.S. Census Bureau's 2025 Population Estimates Program (PEP), which provides annual estimates of the resident population for every county in the United States. Unless otherwise noted, comparisons reflect changes between July 1, 2024 and July 1, 2025. Additional demographic, economic and fiscal indicators are available through NACo's County Explorer.
Notes
- Each year, the U.S. Census Bureau's Population Estimates Program (PEP) uses current data on births, deaths and migration to estimate population change since the most recent decennial census and produce annual estimates of population, demographic components of change and housing units.
- Each annual release is referred to as a vintage and begins with the most recent decennial census before extending through the current estimate year. For example, the Vintage 2025 series includes estimates as of July 1, 2025.
- Unless otherwise noted, analyses are based on 3,069 counties with active county governments. Connecticut, Rhode Island and portions of Alaska and Massachusetts are excluded because they do not have active county governments. Independent cities in Virginia are also excluded.
- Population size categories and growth classifications follow NACo County Explorer methodology. Small counties have fewer than 50,000 residents, medium-sized counties have between 50,000 and 500,000 residents and large counties have more than 500,000 residents. Growing counties are defined as those with annual population growth greater than +0.5 percent, stable counties as those with annual population change between -0.5 percent and +0.5 percent and declining counties as those with annual population change below -0.5 percent.
- For this analysis, NACo groups the Census Bureau's Population Estimates Program county-level age estimates into four categories: children under age 18, young adults ages 18–24, working-age adults ages 25–64 and older adults ages 65 and older. The 25–64 category combines the Census Bureau's 25–44 and 45–64 age groups to provide a broader measure of the working-age population.
About County Explorer
County Explorer is NACo's interactive data platform, providing county-level demographic, economic and fiscal indicators to help county leaders better understand the communities they serve. Visit ce.naco.org to explore population levels and trends, migration patterns, and more for every U.S. county.
Endnotes
- After a historically low population increase of 522,000 in 2021, the U.S. population experienced a strong rebound, growing by 1.9 million in 2022, 2.76 million in 2023, and peaking at 3.25 million in 2024. However, in 2025, this growth momentum reversed, with the country adding only 1.78 million residents, about half the previous year's growth rate. ↩
- Although the natural change, the surplus of births over deaths, has been stable throughout this period, ranging from 146,000 in 2021 to 519,000 in 2025, the slowdown is not about fewer babies or more deaths. It is entirely a migration story. Net international migration, which accounted for between 70% and 88% of the total residents added each year from 2021 through 2024, fell from 2.73 million in 2024 to 1.26 million in 2025 — a 54% drop in a single year. Research at the state level has confirmed the same conclusion: the decline in immigration has reduced national population growth by approximately half, affecting nearly every state. An analysis of county and metropolitan data revealed that all 56 of the nation's largest metropolitan areas experienced a decline in immigration between 2023 and 2024. As a result, all but one of these areas saw slower growth or even an outright loss in population. See Frey, W. H. (2026, April). An immigration slowdown led to widespread declines in population growth in America's major metro areas. Brookings Institution. https://www.brookings.edu/articles/an-immigration-slowdown-led-to-widespread-declines-in-population-growth-in-americas-major-metro-areas ↩
- Rankings of the fastest-growing counties include only counties with populations of 20,000 or more in 2025. This threshold reduces the influence of very small counties, where modest changes in the number of residents can produce disproportionately large percentage changes. ↩
- Domestic migration, the movement of people between counties and states within the country. The dynamics of domestic and international migration as growth drivers have changed significantly over the past five years. In 2021, during the peak of the pandemic, domestic migration was the main factor in 96 percent of counties experiencing growth, while international migration contributed less than 1 percent. As pandemic restrictions eased and relocation flows started to recover, international migration rose from 9 percent of growing counties in 2022 to 28 percent in 2024. However, in 2025, a sharp decline in international migration allowed domestic migration to dominate again at 82 percent. ↩
- For this analysis, counties were classified as growing if their population increased by more than 0.5% between 2024 and 2025. Of the 3,069 counties included in the analysis, 1,032 met this threshold. Natural change or increase: Natural change is the difference between births and deaths in a population. A positive natural change occurs when there are more births than deaths, also referred to as a natural increase. ↩
- For this analysis, counties were classified as declining if their population decreased by more than 0.5% between 2024 and 2025. Of the 3,069 counties included in the analysis, 582 met this threshold. Among the 582 counties that experienced a decline in 2025, domestic out-migration was the principal reason in 61 percent of cases, while natural decrease — meaning more deaths than births — accounted for the remaining 39 percent. International out-migration accounted for fewer than 1 percent of the counties that saw a decline. Notably, deaths outnumbered births in 83 percent of declining counties — but domestic out-migration was large enough to be the dominant force in most of them. ↩
- Riordan Frost, “Declining Immigration Undermines Urban and Rural Population Growth,” Joint Center for Housing Studies Of Harvard University (JCHS), available at https://www.jchs.harvard.edu/blog/declining-immigration-undermines-urban-and-rural-population-growth (June 2026). ↩
- Large suburban counties and smaller metro counties are better equipped for sustained growth due to a combination of domestic migration and natural population increases. See U.S. Census Bureau, “Population Gains in Metro Areas Driven Largely by Growth in the Exurbs This Decade,” available at https://www.census.gov/library/stories/2026/05/major-city-outer-edge-growth.html (May 2026); Jed Kolko, “With less immigration, urban growth slowed in 2025,” Peterson Institute for International Economics, available at https://www.piie.com/blogs/realtime-economics/2026/less-immigration-urban-growth-slowed-2025 (April 2026). ↩
- Small counties gained approximately 108,000 residents through domestic migration in 2025, compared with nearly 600,000 for medium-sized counties. Large counties, by contrast, recorded a net domestic migration loss of approximately 673,000, underscoring that medium-sized counties absorbed the largest share of domestic moves of any size tier. See Jed Kolko, “With less immigration, urban growth slowed in 2025,” Peterson Institute for International Economics, available at https://www.piie.com/blogs/realtime-economics/2026/less-immigration-urban-growth-slowed-2025 (April 2026); Riordan Frost, “Declining Immigration Undermines Urban and Rural Population Growth,” Joint Center for Housing Studies of Harvard University (JCHS), available at https://www.jchs.harvard.edu/blog/declining-immigration-undermines-urban-and-rural-population-growth (June 2026). ↩
- Domestic out-migration from urban counties has been increasing steadily since the early 2010s, driven largely by affordability, with residents relocating to suburban areas and smaller communities. With fewer international migration gains in 2025, the nation's largest counties saw growth diminish or, in some cases, turn to loss. See: Jed Kolko, “With less immigration, urban growth slowed in 2025,” Peterson Institute for International Economics, available at https://www.piie.com/blogs/realtime-economics/2026/less-immigration-urban-growth-slowed-2025 (April 2026). ↩
- The Census Bureau has similarly noted that Southern counties have claimed most of the nation's fastest-growing counties every year since 2020, with growth particularly concentrated in outlying metro counties — places on the outer edges of major metros that have attracted residents across all age groups. See U.S. Census Bureau. (2026, June 25). Populations in all age groups growing in the South, driven by outlying counties in metro areas. https://www.census.gov/newsroom/press-releases/2026/vintage-2025-pop-estimates.html ↩
- In 2025, migration significantly affected regional population shifts, especially in the South, which accounted for about 67 percent of county-level population gains with an increase of approximately 1.16 million residents. This resulted in a growth rate of 0.89 percent, nearly three times that of other regions. Southern growth was driven by net migration of over 950,000, with both domestic (365,000) and international (585,427) factors contributing positively. Texas, Florida, and North Carolina were the top states, adding over 391,000, nearly 197,000, and around 146,000 residents, respectively. ↩
- California significantly impacted this trend, as the state alone lost 229,000 residents to domestic out-migration, more than offsetting gains elsewhere in the region. The West overall recorded net domestic out-migration of approximately 169,000 residents in 2025; subtracting California's loss of 229,000 leaves the remaining 13 states with a net domestic migration gain of approximately 60,000 residents −169,000−(−229,000) =+60,000, with Arizona (+31,000), Idaho (+20,000), and Nevada (+15,000) leading in net gains. Washington (+73,000), Arizona (+67,000) and Utah (nearly 36,000) led the West in total population gains. ↩
- The Midwest gained nearly 232,000 residents in 2025, supported by international migration (nearly +174,000), natural increase (+40,000) and, for the first time this decade, positive domestic migration (+16,000). Ohio (nearly 40,000), Indiana (nearly 39,000) and Minnesota (33,000) led the Midwest in total population gains. See: William H. Frey, “An immigration slowdown led to widespread declines in population growth in America’s major metro areas,” available at https://www.brookings.edu/articles/an-immigration-slowdown-led-to-widespread-declines-in-population-growth-in-americas-major-metro-areas/ (April 2026). ↩
- The Northeast gained nearly 199,000 residents through international migration and another 52,000 through natural increase, which offset the region's domestic migration loss of nearly 179,000 residents. New Jersey was the only Northeastern state among the top 10 states nationally for population gains, adding 42,000 residents. ↩
- The nation's senior population grew by more than 8.3 million residents, 15.5 percent, between 2020 and 2025. Jasper County, S.C., led all counties nationally with a 62.6 percent increase in its senior population, followed by Goochland County, Va. (53.1 percent) and Camas County, Idaho (47.9 percent). Four of the top 10 fastest-aging counties are in the South, including Fort Bend County, Texas, the only large county on the list, where the senior population grew from 100,726 to 138,013 — an increase of more than 37,000 seniors in five years. ↩
- The number of U.S. residents under age 18 fell by nearly 1.5 million, a 2.2 percent decline, between 2020 and 2025. ↩
- U.S. Census Bureau, “Populations in All Age Groups Growing in the South, Driven by Outlying Counties in Metro Areas,” available at https://www.census.gov/newsroom/press-releases/2026/vintage-2025-pop-estimates.html (June 2026); Russell Contreras, “The South is escaping America's youth implosion,” available at https://www.axios.com/2026/06/25/south-child-population-census (June 2026); and Mike Stobbe, “The U.S. fertility rate reached a new low in 2024, CDC data shows,” available at https://www.pbs.org/newshour/nation/the-u-s-fertility-rate-reached-a-new-low-in-2024-cdc-data-shows (July 2025). ↩
- Small counties (population under 50,000) lost working-age population in the aggregate, declining from 18,572,000 in 2020 to 18,147,480 in 2025, a decrease of 2.3%. Medium-sized counties (50,000-500,000) grew in the aggregate, from 59,812,485 to 61,081,352 (+2.1%), and large counties (500,000+) also grew, from 86,341,542 to 87,997,659 (+1.9%). At the county level, 76% of small counties, 50% of medium-sized counties, and 39% of large counties experienced a decline in the working-age population between 2020 and 2025. ↩
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