King County is still growing — just not quite like it had been.
According to data released Thursday by the U.S. Census Bureau, King County’s population grew by about 27,000 from July 1, 2024, to July 1, 2025, for a growth rate of 1.2%.
That’s a solid increase, but it was slower than the previous year’s gain of about 34,900 people and 1.5% growth rate. The Census Bureau downwardly revised last year's growth — it had originally been estimated at 43,400.
King County remained the nation’s 13th-largest county, with a total population of 2.34 million.
Nationally, many of the country’s largest counties continued to grow last year, though the gains were more modest than in some recent periods. Consistent with the pattern in recent years, the strongest growth was in the Sun Belt, with its combination of sunshine and relatively affordable housing.
For numeric growth, King County ranked sixth last year, and was the only county outside the Sun Belt to crack the top 10. That is impressive, especially given that we don't have a warm, sunny climate and our cost of living is among the highest in the country.
Harris County, Texas, home to Houston, led the nation in numeric growth for the fourth straight year, with a nearly 49,000-person increase. Other big gainers included Collin County, Texas, in the Dallas area; Maricopa County, Ariz., which includes Phoenix; and Wake County, N.C., which includes Raleigh.
At the other end of the spectrum, Los Angeles County posted the nation’s largest numeric decline, losing more than 53,000 residents. Other counties with large losses were in Florida: Pinellas County, where St. Petersburg is located, and Miami-Dade County. Florida had been one of the fastest-growing states, but its growth rate slowed considerably in 2025.
In King County, international arrivals remained the dominant driver of growth, though that flow slowed considerably last year. The county added about 28,400 people through net international migration — down sharply from more than 40,000 the year before. Natural increase (births minus deaths) held steady at roughly 7,400, with about 22,800 births and 15,300 deaths recorded among county residents.
Domestic migration, meanwhile, showed a bit of improvement. The county still lost people to other U.S. counties — a net loss of about 9,100 residents — but that decline was smaller than the roughly 12,700-person loss the previous year.
The Census Bureau doesn’t break out the specific countries immigrants came from, nor does it tell us exactly where the people leaving for other U.S. counties went. But we do know that King County typically has the greatest net domestic losses to neighboring Pierce and Snohomish counties, where housing costs are lower.
Snohomish County, for its part, added about 9,600 residents last year for a growth rate of 1.1%. Pierce County grew by roughly 6,500 people, or 0.7%.
King County grew faster than Washington as a whole. Data released by the Census Bureau earlier this year showed the state's population increased by 0.9% from July 1, 2024 to July 1, 2025.
Within Washington, King wasn’t the fastest-growing county — that honor went to sparsely populated Columbia County in Eastern Washington, which led with a 2.4% jump — but that's only an increase of 95 people, bringing the county's total population to a mere 4,100. It was followed by Douglas County at 2.1% and Mason County at just over 2%. Okanogan County, which topped the list the previous year, grew at a more modest 1.3%.
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