The largest county in Washington
There are two right answers. By land area it is Okanogan County; by population it is King County. Which one you want depends on what you meant by largest.
Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025. Retrieved 30 August 2026.
By land area
| Rank | Name | Land area | Population |
|---|---|---|---|
| 1 | Okanogan County | 5,266 sq mi | 45,230 |
| 2 | Yakima County | 4,295 sq mi | 259,185 |
| 3 | Chelan County | 2,921 sq mi | 81,941 |
| 4 | Grant County | 2,680 sq mi | 105,727 |
| 5 | Stevens County | 2,477 sq mi | 49,668 |
| 6 | Lewis County | 2,403 sq mi | 88,062 |
| 7 | Lincoln County | 2,311 sq mi | 11,982 |
| 8 | Kittitas County | 2,297 sq mi | 48,803 |
| 9 | Ferry County | 2,203 sq mi | 7,517 |
| 10 | Whitman County | 2,159 sq mi | 48,512 |
By population
| Rank | Name | Population | Density |
|---|---|---|---|
| 1 | King County | 2,344,939 | 1,108 per sq mi |
| 2 | Pierce County | 946,288 | 567 per sq mi |
| 3 | Snohomish County | 870,656 | 417 per sq mi |
| 4 | Spokane County | 558,344 | 316 per sq mi |
| 5 | Clark County | 532,119 | 847 per sq mi |
| 6 | Thurston County | 304,261 | 421 per sq mi |
| 7 | Kitsap County | 283,374 | 717 per sq mi |
| 8 | Yakima County | 259,185 | 60.4 per sq mi |
| 9 | Whatcom County | 236,392 | 112 per sq mi |
| 10 | Benton County | 221,722 | 130 per sq mi |
And the smallest
More on Washington
Rebuilt from source data 30 August 2026. How these figures are produced.