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DENVER (KDVR) — More data is coming in that suggests Colorado’s decade-long population eruption has ended.

The U.S. Census Bureau and the Colorado State Demography Office don’t have 2021 migration data yet, but independent researchers found more people moving out of Colorado than in over the year. Census data deepens a picture of people moving out of Denver and some of its surrounding counties and into adjacent ones.

HireAHelper, an online moving service, analyzed over 90,000 moves that took place over 2021. In Colorado, 15% more people moved out of the state than into it over the year.

This outflux is a turnabout from the 2010s, during which Colorado gained 750,000 people. State demographers had warned that the trend was slowing in the late 2010s and early 2020s, despite the homebuying melee brought on by out-of-towners looking for outdoors adjacent homes.

Colorado gained 27,761 people in 2021, which is the smallest population gain since 1990. Colorado’s population growth peaked in 2015 with nearly 100,000 more residents and has slowed most years since then.

Migration data from the previous year explains some of what’s happening within the state itself.

Some Denver metro counties in particular are losing people to farther-flung counties south and north of the metro area.

Collectively, over 16,000 more people left Adams, Arapahoe, Boulder, Denver and Jefferson counties from 2020 to 2021 than moved in, led by Denver, Boulder and Jefferson.

Denver lost the most, with 8,867 moving out of the county. Jefferson saw 3,414 move out, Arapahoe 2,285, Boulder 1,413 and Adams 468.

In contrast, Douglas, Weld, El Paso, Larimer, Mesa and Pueblo counties saw more people move in. Over 7,500 more people moved into Douglas County than left, followed by Weld County with 6,730 and El Paso County with 2,988. Larimer County had 2,602 new residents and Mesa County had 1,738.