Colorado’s population growth has slowed sharply this decade compared to last, and would have fallen even more except for a strong surge in international migration following the pandemic. But a sharp decline in the number of people moving to the U.S. from other countries, combined with outflows because of deportations and voluntary departures, is forcing state demographers to recalibrate their forecasts.
“We need to adjust expectations in terms of the low migration rates,” said Neal Marquez, State Forecast Demographer, during the 2025 Demography Summit held in Arvada on Nov. 7.
State and local officials will need to rethink how many schools are needed to accommodate a shrinking population of children and teenagers, how many adult workers will be available to fill jobs, including health care staff to care for an aging population, and how many homes and apartments will need to be built.
After dissecting some of the latest Census numbers, Marquez predicts the state will have 120,000 fewer people by 2029 and 200,000 fewer by 2050 than what was forecast last year. Because of lower international immigration, the demography office has reduced its forecast for the state’s crossover point, when deaths exceed births, from 2051 to 2048.
Once a top 10 state for population growth, Colorado is now tracking the national average and could fall below it unless it finds a way to boost births and attract more residents from elsewhere. Before 2020, drawing residents wasn’t much of a problem, so much so that there was strong pushback to population growth. But a lot has changed.
Colorado, once popular with young adults relocating from other states, now finds itself at a disadvantage because of significantly higher housing costs and anemic job growth. Slower population gains in the U.S. mean fewer young adults available to move and tougher competition to get them. And more older residents are leaving the state, which has contributed to a smaller net domestic migration number.
Since 2022, international migration has been the single most important factor in Colorado’s population growth, and that could soon reverse.
Before the pandemic, about 80% of the net migrants coming to the state were relocating from other states, and 20% were coming from abroad. But that ratio has completely flipped, with 80% of net migration international and only 20% domestic, Marquez said.
For the past three years, the U.S. Census Bureau and state demographers have underestimated just how many people have moved to the state from other countries. Revisions have boosted the number of international migrants by significant amounts.
Census population counts are made between June 30 and July 1 in what are known as vintages. Initial estimates for the 2023 population vintage for Colorado were off by 14,233 people due to undercounting of international migration. Last year, estimates were off by 24,133, or 43% of the updated population count, which is now at 56,039.
“Domestic migration is relatively low. It is international migration where we see these big increases,” said Nancy Gedeon, Estimates Demographer, during her presentation at the Summit.
Demographers have long struggled to obtain a firm count on international migration, but before 2022, they felt they could rely on the American Community Survey from the U.S. Census Bureau. Also, when international transplants were only 20% of total net migration in Colorado, the impact of being wrong mattered less in determining overall population counts.
Gedeon said the population estimates felt off, and that growth was higher than what the numbers were capturing. A deeper dive by the Census Bureau on international immigration confirmed why.
Traditional migration from sending countries such as Mexico, India, China and the Philippines rebounded after the pandemic. But it was surpassed by a surge in migrants from countries in turmoil, places such as Afghanistan, Haiti, Cuba, Ukraine and Venezuela. An estimated 400,000 Venezuelans came to the U.S. in 2023 and 2024, initially by showing up at the border seeking asylum or crossing illegally and later through the Temporary Protected Status program, which was expanded under the Biden administration.
Colorado, especially Denver, was a key destination in the region for the recent wave of international migrants. Using U.S. Customs and Border Protection data, The Associated Press estimates 2.5 million people crossed the border illegally or came through an online appointment app called CBP One between May 12, 2023, and Jan. 18, 2025.
Metro Denver’s share of that surge measured 50,280 based on addresses provided, which ranked 8th highest among metro areas. On a per capita basis, the Denver area ranked 4th highest for the inflow. It isn’t known how many of those migrants ended up staying or moved on.
The newer migrants are less likely to be captured in Census surveys and more traditional channels, which resulted in an undercount. But now that international migration is drying up, demographers are scrambling to avoid a different problem — overcounting.
Broomfield economist Gary Horvath said the state demography office has worked hard to get a better grip on international migration under new State Demographer Kate Watkins and Marquez, the new projections demographer.
“It is a step in the right direction to produce international immigration numbers. More information is needed about the immigrants. I don’t know if it is possible to collect the needed details, but SDO is now getting some information,” Horvath said.
And it continues to be important now that the international migration trends are reversing, which could reduce how much the state grows in the years ahead.
The Pew Research Center estimates that the number of foreign-born residents in the U.S. has fallen from a record 53.3 million in January of this year to 51.9 million in June. If that trend continues across the second half of the year, it would mark the first time net international migration to the U.S. has gone negative since the Great Depression.
The San Francisco Federal Reserve predicts net international migration to the U.S. could fall to around 1 million this year, down from 2.6 million in 2024 and 3.5 million in 2023. Much of the decline reflects a sharp drop in the number of illegal crossings and asylum cases, combined with a more robust effort under the Trump administration to round up those who arrived via those routes in prior years.
A big drop carries big implications for Colorado, which has relied heavily on net migration, primarily from abroad, to sustain its population gains in the years following the pandemic.
In raw numbers, Colorado’s population gains appeared close to matching 2019 levels, although the growth rate remains below what it was last decade. Forecasts of slow and steady growth moving forward are now being lowered.
Different counties will be impacted differently by slower international migration, Marquez said. Weld, Douglas and Broomfield counties are expected to see the strongest population growth going forward, in part because they fare better at attracting growing families from more urban areas and people relocating from other states.
But if Colorado reached zero net migration in the years ahead, then most of the state would see population declines. Last year, 10 Colorado counties would have lost population absent the surge in international immigration and another 13 counties with falling populations would have seen even larger declines, according to an analysis from the Population Reference Bureau.
Most of the counties are rural, but Jefferson, Boulder and Arapahoe counties are among the counties that avoided depopulation because of international migration, the study found.
“The only way the population can continue to grow is via net migration,” Marquez said. This decade, net migration in Colorado is largely international, which alone accounted for 57% of the population gains in the state last year.
To put the numbers in perspective, the state gained 5,400 people from net domestic migration last year, 17,300 from natural increase, or births minus deaths, and 32,200 from net international migration.
Net migration this year to Colorado is likely to be only half of what it was in 2015, according to an analysis in July from the Common Sense Institute. In metro Denver, the decline is running closer to 70%.
“These migration trends carry significant economic implications: a shrinking inflow of new residents can limit labor force growth, dampen housing demand, and reduce overall economic dynamism – particularly in sectors reliant on a growing and mobile population,” according to the report’s authors.
In the past few years, the State Demography Office viewed the drop in net migration as a temporary distortion caused by the pandemic. They had forecast a rebound to 29,272 net migrants moving into Denver by 2029, ahead of a slow tapering down to around 12,000 net migrants in 2050.
Unless housing supply can be boosted and costs brought into line with national averages, Colorado will likely have difficulty when it comes to drawing residents from states with lower living costs. And Marquez holds little hope that a new baby boom will reverse the situation.
A fertility rate of 2.1 children per woman is considered a level needed for the population to replace itself and stay steady. But Colorado and the U.S. haven’t seen that since the early 2000s. The rate is now closer to 1.6. Based on countries that are ahead of Colorado on the demographic decline curve, the best the state can hope for is that birth rates don’t drop too much more.
After a brief decline following a surge during the pandemic, the number of deaths in the state is expected to increase in the years ahead.
Foreign workers in particular have played a critical role in constructing the state’s buildings and infrastructure, in harvesting its crops, in staffing its hotels and hospitals and providing technology companies with a competitive edge. They represented about half of the total gain in new workers in the U.S. labor force between 2022 to 2024, according to the San Francisco Fed’s analysis. As the flows dry up, that will likely mean fewer new workers and a tighter labor market. But it could also lead to stronger wage gains and relief from the housing shortfall.
With international immigration dropping off sharply, the realization has dawned that much slower growth may represent the new normal for Colorado, not a temporary aberration as demographers once thought.
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