Seattle kept adding people in 2025, roughly 18,900 new residents, but the pace of growth clearly eased compared with recent years. That cooler tempo is more than a rounding error, it has real implications for housing construction, transit planning and a downtown that is still absorbing a wave of new apartments and a softer office market.
Official counts: Seattle tops 816,600
According to the latest estimates from the Washington State Office of Financial Management, Seattle's population was about 816,600 on April 1, 2025, an increase of roughly 18,900 residents from the year before. The agency notes that net migration remained the biggest source of growth even as overall statewide growth slowed to around 1 percent.
CoStar: gains cluster around light-rail corridors
An analysis published May 18 by Elliott Krivenko at CoStar found that year-over-year growth rates tapered in 2025, even as certain neighborhoods kept pulling in new residents. The report notes that long-run gains have concentrated around light-rail corridors, underscoring how powerful transit-accessible housing has become in shaping where people land.
Migration and the office market
Local reporting and analysts tie the slower growth to a pullback in international migration along with tech-sector downsizing that has eased demand for downtown offices. KUOW reviewed the migration figures in the state estimates, while Axios highlighted CoStar data pointing to elevated office vacancies and downward pressure on downtown rents.
Housing deliveries still driving growth
State figures also show that growth in new housing units was a principal driver of Seattle's population gains, as well as in other fast-growing cities, according to the Office of Financial Management. That pattern suggests many of the year's new arrivals moved into recently completed apartments and condos, rather than signaling a broad reversal of earlier domestic out-migration trends.
What to watch next
Local outlets noted that Seattle's estimated population has now crossed the 800,000 mark, a psychological milestone as much as a planning one. City planners say the coming year will largely hinge on immigration flows, the timing of new housing deliveries and whether employers bring more workers back to downtown offices. Coverage from The Urbanist and others suggests that transit-oriented development and the city's permit pipeline will be central to how Seattle adjusts to a slower, but still positive, growth trend.
