Washington Counties by Population (2025)

There are 39 counties in Washington.

King County is the largest county in the state, with a population of 2,283,518. The most recent census shows that its population has increased by 0.00% 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 : 933,130
• Snohomish County : 853,379

Washington Counties with the Fewest Residents

The smallest county in Washington is Garfield County, with a population of just 2,375. This total represents a increase of 0.0% since the last census count was performed.

Other small counties include:

• Columbia County : 4,107
• Wahkiakum County : 4,919
• Ferry County : 7,555

Washington Counties with Rapid Growth

Wahkiakum County, with its current population of 4,919, has shown the largest population growth, with an increase of 0.1% since the last census.

Clark County has also had relatively high population growth of 0.05% with 529,976 residents.

On the other hand, Walla Walla County has had the largest decrease in population, with its 60,998 current residents totalling 0.0% less than the previous census.