Amid another modest increase in Oregon’s overall population last year, the biggest growth occurred in the suburbs surrounding Portland.

The figures come from Portland State University’s Population Research Center, which releases yearly population estimates for every city, town and county in the state. Each year, Oregon lawmakers and state officials rely on PSU’s data in crafting legislation and other state policies. At the federal level, officials rely on separate data from the U.S. Census Bureau.

In a press release accompanying the data from PSU, the research team noted that the state continued its trend of “natural population decrease” for the year ending in June 30, 2025. Natural decrease occurs when deaths in the state outnumber births. In the past year, 42,136 people died in Oregon compared to 39,302 who were born.

“This phenomenon of ‘natural decrease’ means that Oregon has become dependent on net in-migration for population growth,” the press release stated. “The natural decrease in the past year was offset by a net migration of approximately 17,000 new residents to the state.”

To make these estimates, researchers analyze data from three Oregon departments: Transportation, Revenue and Education, as well as three federal agencies: the Internal Revenue Services, the Census Bureau and Customs and Border Protection.

According to PSU’s numbers, which were released earlier this month, Washington County saw the greatest overall population increase, adding more than 4,000 residents. Multnomah — which added 2,200 — and Clackamas — which added 1,400 — were also among the top five counties with the greatest population growth.

Within Washington County, Hillsboro added more than 1,000 residents to reach a population of 112,035. Beaverton surpassed 100,000 residents for the first time.

Happy Valley also continued a trend of steady population growth, slowing only slightly from the rate seen between 2020 and 2025. The Clackamas County city now has an estimated 28,291 residents, up from 27,727 last year and up more than 5% from 2020 when the population was 23,949.

Jake Procino, a workforce analyst and economist at Multnomah County, suspects housing availability may be a key factor driving people to the suburbs.

“I suspect that Portland suburbs tend to have larger or cheaper housing than the city of Portland,” Procino told OPB via email.

Though most of the state’s growth occurred outside of Portland, the Rose City also saw a small population increase. Portland added 1,221 residents or 0.2% of its total population over the past year. The city now has an estimated population of 640,623.

While much of the past year’s growth occurred in the Portland metro area, small towns like Yamhill and Adair Village also saw significant increases. Yamhill saw a 7% increase while Adair Village, near Corvallis, grew by 6%.

News Source : https://www.opb.org/article/2025/12/30/portlands-suburbs-grew-the-most-as-oregons-population-grew-modestly-in-2025/