Colorado’s population broke 6 million in 2025, according to the latest U.S. Census estimates.
But the state crawled past that milestone with an annual growth rate of just 0.4%, its slowest in decades. Once a red-hot center for growth, the state is now lagging behind the national growth rate of 0.5%, and it is losing population to Texas and other destinations.
It’s Colorado’s lowest estimated growth rate since 1989.
“We have definitely slowed in the growth categories,” said State Demographer Kate Watkins. “We have slowed relative to other states. We also have come off a period of strong growth.”
Colorado ranks 29th nationally for its growth rate in the year leading up to July 1, 2025. The states with the highest growth rates are South Carolina, Idaho, North Carolina and Texas.
The slowdown is a result of two significant changes. The first is that people are leaving Colorado for other states at a rate not seen in decades. Colorado had a net loss of 12,000 residents to other states. In other words, thousands more people moved out of Colorado than into it. (That was somewhat offset by the arrival of more immigrants from other countries.)
It marks a dramatic turnaround from the 2010s, when the state gained up to 56,000 people from domestic migration each year. The arrival of transplants slowed after the pandemic to just a few thousand per year. But 2025 was the first time in decades that the state recorded a loss to other states.
While it’s hard to say exactly why people are leaving, high housing prices and growing crowds are commonly cited reasons, among others. They may also be leaving for jobs elsewhere, Watkins said.
And some of those ex-Coloradans may have lived here only a short time, Watkins noted – the departures include recent immigrants from other countries, who arrived in very large numbers in 2023 and 2024 and may have moved on to other states by 2025.
International immigration to Colorado has since slowed dramatically, as it has in other states. The number of yearly immigrant arrivals dove from a peak of more than 50,000 in 2023-24 to just about 15,000 in the latest annual estimates.
The new data covers July 1, 2024, to July 1, 2025, a period in which former President Joe Biden tightened immigration policies, and then President Donald Trump began a more dramatic crackdown.
Still, international immigration was “a little higher from our national historical numbers,” Watkins said. She noted that immigrants seeking humanitarian relief – which generally includes many people from South America – “are still making up a considerable or elevated share of that portion.”
Combining all forms of migration, the state gained just 3,300 residents from other states and nations. That’s the slowest rate of arrivals in more than three decades, since the population bust of the 1980s, according to records from the State Demographer’s Office.
The main reason that Colorado’s population still grew was the circle of life. There were more births than deaths, resulting in “natural” population growth of more than 20,000, making up the vast majority of the roughly 24,000 new residents of Colorado in 2024-25. We’ll see if they stick around.
“A pretty decent boost in births,” Watkins said. “It would be Millennials aging up. It could also be some other factors like the insurance coverage of (in vitro fertilization).”
The Denver metro area has attracted most of the state’s population growth in recent years, followed by Greeley and Colorado Springs. The Census has not yet released estimates about how cities and metropolitan areas grew in 2025.
But there are some indications that the Denver area continues to draw new residents from other areas, even as the scales shift for Colorado. A new Bank of America report found that the Denver metro was attracting transplants at the third fastest rate in the nation. The study ranked domestic migration for 2024-25 as a percentage of population for major metropolitan areas.
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