Colorado's population broke 6 million in 2025, according to the latest U.S. Census Bureau estimates, though its annual growth rate of just 0.4% marked its slowest in decades.
The state's 24,000 new residents are the lowest increase since 1990, while the growth rate fell to 0.4% in 2025 from 1.29% in 2024.
The data, which covers July 1, 2024 to July 1, 2025, showed that Colorado had a net loss of 12,000 residents to other states.
"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."
The U.S. population reached nearly 342 million people in 2025, according to population estimates released Tuesday by the U.S. Census Bureau.
The 0.5% growth rate for 2025 was a sharp drop from 2024's almost 1% growth rate, which was the highest in two decades and was fueled by immigration.
The 2024 estimates put the U.S. population at 340 million people.
Immigration increased by almost 1.3 million people last year, compared with 2024's increase of almost 2.8 million people.
If trends continue, the annual gain from immigrants by mid-2026 will drop to only 321,000 people, according to the Census Bureau, whose estimates do not distinguish between legal and illegal immigration.
"The slowdown in U.S. population growth is largely due to a historic decline in net international migration, which dropped from 2.7 million to 1.3 million in the period from July 2024 through June 2025," said Christine Hartley, assistant division chief for Estimates and Projections at the Census Bureau.
"With births and deaths remaining relatively stable compared to the prior year, the sharp decline in net international migration is the main reason for the slower growth rate we see today."
In the past 125 years, the lowest growth rate was in 2021, during the height of the coronavirus pandemic, when the U.S. population grew by just 0.16%, or 522,000 people and immigration increased by just 376,000 people because of travel restrictions into the U.S.
Before that, the lowest growth rate was just under 0.5% in 1919 at the height of the Spanish flu.
The Associated Press contributed to this report.
Solange Reyner ✉
Solange Reyner is a writer and editor for Newsmax. She has more than 15 years in the journalism industry reporting and covering news, sports and politics.
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