Washington Counties by Population (2025)

There are 39 counties in Washington.

King County is the largest county in the state, with a population of 2,383,609. The most recent census shows that its population has increased by 0.05% 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 : 950,622
• Snohomish County : 877,929

Washington Counties with the Fewest Residents

The smallest county in Washington is Garfield County , with a population of just 2,448. This total represents a increase of 0.1% since the last census count was performed.

Other small counties include:

• Columbia County : 3,995
• Wahkiakum County : 4,833
• Ferry County : 7,614

Washington Counties with Rapid Growth

Lincoln County , with its current population of 11,964, 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 0.06% with 877,929 residents.

On the other hand, Island County has had the largest decrease in population, with its 86,587 current residents totalling 0.0% less than the previous census.