Colorado's population topped 6 million for the first time last year, even as growth slowed to a glacial pace, new Census Bureau estimates show.
Why it matters: The state's 24,000 new residents are the lowest increase since 1990 amid the oil and gas industry's collapse.
By the numbers: The state's growth rate fell to 0.4% in 2025 from 1.29% the year prior.
Driving the news: Most of Colorado's growth came from natural increases (21,000), which is birth minus deaths, while migration into the state (15,000) barely exceeded the number of people leaving (12,000).
International immigration is the traditional driver of population increases, but the U.S. saw a historic decline amid tougher U.S. policies.
The big picture: The U.S. population grew just 0.5% from July 2024 to July 2025, adding 1.8 million people.— the slowest rate since the worst of the COVID-19 pandemic, when the population grew by an anemic 0.2%.
The fastest-growing states were South Carolina (+1.5%), fueled largely by domestic migration. Idaho (+1.4%) and North Carolina (+1.3%).
Shrinking states included California, Hawai'i, New Mexico, Vermont and West Virginia.