City and county, 1990 to 2026
Seattle had 823,400 residents on April 1, 2026, and King County 2,424,700. Since 1990 the city has grown 59% and the county 61%.
Put the two on one chart and a question falls out that neither answers alone: is Seattle absorbing the region’s growth, or exporting it? The city holds 34.0% of the county’s people today. That share fell for decades as the suburbs filled, and it has been climbing back since the 2010s — the reversal is the story in this pair of lines, and it is the demographic fact underneath every argument this city has about density.
These are Washington OFM’s April 1 estimates, the official series used to allocate state revenue, so they are re-based whenever a decennial census lands. The annual population post covers the latest year on its own; this is the long view.
Source: Washington State Office of Financial Management, April 1 official population estimates for the city of Seattle and King County. Auto-generated each build.