County facts · Land area · October 21, 2026
Largest Counties in Washington by Area and Population
The largest Washington counties by land area and by 2023 population, plus the smallest, county seats and a link to each official parcel map.
Looking for the largest counties in Washington? Washington has 39 counties covering about 66,455 square miles of land, based on the Census Bureau's 2020 Gazetteer. The largest by land area is Okanogan County, at about 5,266 square miles, roughly 30 times the size of the smallest, San Juan County (174 sq mi). Measured by people instead, the largest is King County, with about 2,271,380 residents in the Census Bureau's July 1, 2023 estimate.
Each table below links the county's Platbookmapper page and its official parcel viewer, so you can go straight from the numbers to the property lines.
Washington counties at a glance
- Counties: 39
- Land area: about 66,455 sq mi, plus about 4,845 sq mi of water inside county lines
- Residents, 2023 estimates: about 7,812,880, or about 118 people per square mile of land
- Median county land area: about 1,739 sq mi
- With a verified public parcel viewer in our directory: 38 of 39 (16 of them through a statewide viewer)
The 10 largest Washington counties by land area
| # | County | Seat | Land (sq mi) | 2023 pop. | People per sq mi | Parcel viewer |
|---|---|---|---|---|---|---|
| 1 | Okanogan County | Okanogan | 5,266 | 43,712 | 8.3 | Washington Current Parcels layer in ArcGIS Map Viewer |
| 2 | Yakima County | Yakima | 4,295 | 256,643 | 60 | listed link under review |
| 3 | Chelan County | Wenatchee | 2,921 | 79,997 | 27 | county web map |
| 4 | Grant County | Ephrata | 2,680 | 102,678 | 38 | Washington Current Parcels layer in ArcGIS Map Viewer |
| 5 | Stevens County | Colville | 2,477 | 48,837 | 20 | Washington Current Parcels layer in ArcGIS Map Viewer |
| 6 | Lewis County | Chehalis | 2,403 | 86,154 | 36 | county web map |
| 7 | Lincoln County | Davenport | 2,311 | 11,738 | 5.1 | Washington Current Parcels layer in ArcGIS Map Viewer |
| 8 | Kittitas County | Ellensburg | 2,297 | 45,508 | 20 | ArcGIS Web AppBuilder |
| 9 | Ferry County | Republic | 2,203 | 7,497 | 3.4 | ArcGIS Web AppBuilder |
| 10 | Whitman County | Colfax | 2,159 | 48,012 | 22 | Washington Current Parcels layer in ArcGIS Map Viewer |
Together these 10 cover about 44% of Washington's land area and hold about 9% of its residents.
The 10 most populous Washington counties
| # | County | Seat | 2023 pop. | Land (sq mi) | Parcel viewer |
|---|---|---|---|---|---|
| 1 | King County | Seattle | 2,271,380 | 2,115 | county web map |
| 2 | Pierce County | Tacoma | 928,696 | 1,668 | county web map |
| 3 | Snohomish County | Everett | 844,761 | 2,087 | ArcGIS Experience Builder |
| 4 | Spokane County | Spokane | 551,455 | 1,764 | county web map |
| 5 | Clark County | Vancouver | 521,150 | 628 | county web map |
| 6 | Thurston County | Olympia | 299,003 | 722 | county web map |
| 7 | Kitsap County | Port Orchard | 277,658 | 395 | county web map |
| 8 | Yakima County | Yakima | 256,643 | 4,295 | listed link under review |
| 9 | Whatcom County | Bellingham | 231,919 | 2,108 | ArcGIS Experience Builder |
| 10 | Benton County | Prosser | 215,219 | 1,700 | county web map |
These 10 hold about 82% of Washington's residents in the 2023 estimates.
The 5 smallest Washington counties by land area
| County | Seat | Land (sq mi) | 2023 pop. | Parcel viewer |
|---|---|---|---|---|
| San Juan County | Friday Harbor | 174 | 18,566 | Washington Current Parcels layer in ArcGIS Map Viewer |
| Island County | Coupeville | 208 | 86,267 | ArcGIS Experience Builder |
| Wahkiakum County | Cathlamet | 263 | 4,765 | ArcGIS Experience Builder |
| Kitsap County | Port Orchard | 395 | 277,658 | county web map |
| Clark County | Vancouver | 628 | 521,150 | county web map |
Most and least crowded
- Most people per square mile: King County, about 1,074 (then Clark County, 829, and Kitsap County, 703)
- Fewest people per square mile: Garfield County, about 3.3 (then Ferry County, 3.4, and Columbia County, 4.7)
Counties with the most water
The Census Bureau reports water separately from land. It counts lakes, reservoirs, rivers and, for coastal and Great Lakes counties, the water inside the county boundary.
- Clallam County: about 930 sq mi of water, 35% of its total area
- San Juan County: about 447 sq mi of water, 72% of its total area
- Whatcom County: about 397 sq mi of water, 16% of its total area
Using these numbers in a land search
- Land area is not parcel count. A large rural county can hold fewer parcels than a small suburban one, so size alone says little about how busy its parcel map is.
- Search, don't scroll. In a big county, type an address, owner name or parcel number into the viewer's search box, where it has one, instead of panning across the map.
- Records follow the county line. Deeds, plats and tax bills are kept by the county where the parcel sits, so a tract that crosses a county line usually has a parcel number in each county.
- Rounded figures. Land and water areas are rounded to whole square miles. People per square mile is the 2023 estimate divided by land area.
Related guides
- Washington county GIS websites by viewer
- Washington plat maps
- Washington statewide parcel map
- Washington landowner maps for hunting
- Oregon–Washington border counties
More: All Washington counties on Platbookmapper
Sources
- U.S. Census Bureau Gazetteer files, 2020 county land and water area.
- U.S. Census Bureau, Population Estimates Program, county totals, Vintage 2023 (July 1, 2023 estimates)
- Platbookmapper county GIS directory (live data file behind our county pages, pulled October 21, 2026) for each county's official parcel viewer.
- County seats: Wikidata (county seat property), cross-checked against Census place names.