Washington Counties by Population (2026)

There are 39 counties in Washington.

King County is the largest county in the state, with a population of 2,427,007. The most recent census shows that its population has increased by 0.07% since the previous census.

A number of other Washington counties also boast relatively large populations for their state, though not able to match the density of King County:

• Pierce County : 960,074
• Snohomish County : 891,745

Washington Counties with the Fewest Residents

The smallest county in Washington is Garfield County , with a population of just 2,492. This total represents a increase of 0.1% since the last census count was performed.

Other small counties include:

• Columbia County : 3,965
• Wahkiakum County : 4,866
• Ferry County : 7,685

Washington Counties with Rapid Growth

Okanogan County , with its current population of 46,830, has shown the largest population growth, with an increase of 0.1% since the last census.

Snohomish County has also had relatively high population growth of 0.07% with 891,745 residents.

On the other hand, Island County has had the largest decrease in population, with its 86,696 current residents totalling 0.0% less than the previous census.