Colorado's Population Shifts: County-Level Trends in Migration, Growth, and Change

Introduction

Colorado’s population is still growing, but the geography of that growth has changed. Recent gains are increasingly concentrated in a smaller group of counties, while several large metro and mountain counties are growing slowly, losing population, or attracting fewer net new residents than they did a decade ago. As these patterns continue to evolve, the shifts can have important implications for housing demand, labor markets, and local government planning.

This report examines county-level population and migration trends across Colorado using 2025 State Demography Office data. It focuses on identifying the state’s fastest growing regions, the counties where growth has slowed, and how those patterns have shifted over the past decade. This analysis focuses on the 1-, 3-, 5-, and 10-year changes in population and net migration with the year 2025 as the baseline.

This report does not attempt to isolate the causes of these shifts. However, changes in housing affordability, job location/remote-work patterns, and other factors may all influence where residents choose to live within Colorado.

This report distinguishes between population, net migration, and change in net migration. Population is the total number of people living in a county. Net migration is the number of people moving into a county minus the number moving out during a given period. Change in net migration measures how that net migration figure differs from a prior year.

 Key Findings

Colorado’s statewide growth has slowed. Weld and Douglas counties continue to account for a large share of recent gains, and several large metro and mountain counties are showing flat or negative recent population trends.

Largest Population Increases and Decreases (2024-2025)

Counties with largest population gain:

• Weld County (+8,651)
• Douglas County (+7,181)
• Adams County (+4,836)

Counties with largest population loss:

• Jefferson County (-600)
• Boulder County (-556)
• Eagle County (-481)

Largest Net Migration Increases and Decreases (2024-2025)

Counties with largest net migration gain:

• Weld County (+6,008)
•  Douglas County (+5,306)
• Mesa County (+1,683)

Counties with largest net migration loss:

• Arapahoe County (-1,884)
• Jefferson County (-1,225)
• Denver County (-903)

Migration Slows in Major Metro Counties

• Jefferson County, Colorado’s fourth-most populous county, increased by just 2.24% over the past decade, one of the slowest 10-year growth rates among the state’s largest counties.
• Net migration declined across all of Colorado’s most populous counties between 2015 and 2025.
• Alongside the state’s 80% decline in net migration, two of Colorado’s most populous counties, Arapahoe and Jefferson Counties, saw the steepest declines, -125.9% and -126%, respectively between 2015 and 2025.

Population and Net Migration Declines

• Colorado’s population growth slowed from +83,036 in 2015-16 to +33,151 in 2024-25, marking a decline of roughly 60% over the period.
• Net migration declined from +68,844 in 2015 to +13,568 in 2025, an 80% decrease.

Statewide Population Growth

From 2024 to 2025, Colorado’s population increased by 33,151 individuals. Table 1 shows annual population changes over the past decade. While the state continued to experience population growth from 2024 to 2025, the increase was notably smaller than in recent years and represented the lowest annual growth since the pandemic-era increase of 26,674 individuals from 2020 to 2021.

Table 1: Colorado’s Population Changes Over Time

County-Level Population Growth

In 2025, Weld County experienced the largest change in population, growing by 8,651 individuals. Meanwhile, Jefferson County experienced the least amount of growth, with a decline in population of 600 individuals.

Population trends over the past decade show that Weld County led all counties in growth, with a 32.89% increase. Meanwhile, the statewide change in population saw an increase of 9.97%. Table 2 shows the population changes in Colorado’s most populous counties over a 1-, 3-, 5- and 10- year period. For a fuller picture, Appendix C shows these changes for Colorado’s 64 counties.

Table 2: Population Changes Over Time in Colorado’s Most Populous Counties

*1-year change is from 2024-2025, 3-year change is from 2022-2025, 5-year change is from 2020-2025, and 10-year change is from 2015-2025.

Population growth has slowed across these metropolitan counties over time. Short-term population growth has slowed relative to longer-term trends in these counties.

Among these counties, Jefferson County experienced the lowest 10-year population growth, increasing by just 2.24%. It was also one of the two most populous counties that experienced a decline in one-year population change.

Appendix A illustrates the population patterns across Colorado from 2024 to 2025, with several metro and mountain counties, including Jefferson County, Boulder County, and Eagle County, experiencing population declines, while Weld County led the state in population growth during this period.

State-Level Migration Patterns

In 2024, Colorado’s net migration was 38,860 individuals, whereas in 2025, net migration was 13,586 individuals. Although the state experienced positive net migration in 2025, net migration slowed significantly. A decline of 25,292 individuals suggests that Colorado became a less attractive destination for new residents compared to the previous year.

Table 3: Colorado Net Migration Over Time

Table 3 shows the shift in statewide net migration since 2015. Net migration had not been as low as it was in 2025 since the pandemic-era level in 2021. Also, the statewide change over the past decade reflected an 80% decline, suggesting that the state is no longer attracting new residents at the pace it once did.

County-Level Migration Patterns

At the county level, Weld County recorded the largest net migration gain in 2025, adding 6,008 residents, while Arapahoe County recorded the largest net out-migration, losing 1,884 residents. Appendix B shows the negative and positive net migration changes in all Colorado counties from 2024 to 2025.

Colorado’s most populous counties had lower net migration totals in 2025 than they did in 2015, indicating a slowdown in population inflows. Figure 1 illustrates net migration trends in these counties over the past decade. For a fuller picture, Appendix D illustrates the changes that every Colorado county has experienced with its net migration.

Figure 1: Net Migration by Colorado’s Most Populous Counties Over Time

 Jefferson County recorded the steepest decline in net migration between 2015 and 2025, decreasing by 126%, with Arapahoe County close behind at a 125.9% decline. Because both counties shifted from net in-migration to net out-migration, the percentage decline exceeds 100%.

Notably, none of the most populous counties experienced higher net migration levels in 2025 than in 2015. However, Douglas County experienced only a minimal decline of 1% during this period.

Bottom Line

Colorado remains a growing state, but recent growth is occurring in different places than it did during the state’s peak growth years.

Net migration is far below its mid-2010s level, and many of the state’s largest metro counties are no longer attracting residents at the same pace. At the same time, growth is increasingly concentrated in counties such as Weld and Douglas, which, while benefiting in a multitude of ways from the more rapid population increase, may face greater pressure on housing, transportation, infrastructure, and other services. Counties with slower or negative growth may face a different challenge: maintaining labor-force growth, school enrollment, and tax-base momentum.

Appendix

Appendix A: Population Change by Colorado County

 Appendix B: Net Migration by Colorado County

Appendix C: Population Change in Colorado’s Counties Over Time

*1-year change is from 2024-2025, 3-year change is from 2022-2025, 5-year change is from 2020-2025, and 10-year change is from 2015-2025.

Appendix D: Net Migration Shifts in Colorado's Counties Over Time