What are the fastest-growing counties in Washington?
Lincoln County is the fastest-growing county in Washington: its population grew 1.86% a year from 2020 to 2025, to 11,982 residents (Census PEP Vintage 2025). Douglas County (1.55%) and Mason County (1.51%) follow. Washington as a whole grew 0.70% a year to 8,001,020 residents.
Data as of 2026-09-23. Population, growth and migration: PEP Vintage 2025 · 2020–2025. Income migration: IRS SOI 2022–2023 (2-yr lag).
Top 10 counties in Washington by population growth, 2020 to 2025
| Rank | County | Population | Growth (% per year) | Net domestic migration | Net international migration | IRS net AGI migration |
|---|---|---|---|---|---|---|
| 1 | Lincoln County | 11,982 | 1.86% | +1,210 | +10 | +$5.3M |
| 2 | Douglas County | 46,473 | 1.55% | +1,927 | +1,009 | +$13.1M |
| 3 | Mason County | 71,165 | 1.51% | +4,707 | +1,351 | +$44.3M |
| 4 | Okanogan County | 45,230 | 1.42% | +1,351 | +2,332 | +$12.0M |
| 5 | Pend Oreille County | 14,457 | 1.37% | +1,449 | +10 | +$7.3M |
| 6 | Benton County | 221,722 | 1.34% | +7,439 | +3,752 | +$11.2M |
| 7 | Lewis County | 88,062 | 1.30% | +5,822 | +611 | +$49.3M |
| 8 | Klickitat County | 24,331 | 1.29% | +1,172 | +432 | +$18.8M |
| 9 | Stevens County | 49,668 | 1.29% | +3,608 | +41 | +$16.0M |
| 10 | Grant County | 105,727 | 1.23% | +827 | +2,935 | +$6.3M |
Where are people moving in Washington?
Clark County gained the most people from elsewhere in the United States: net domestic migration of +15,206 from 2020 to 2025 (Census PEP Vintage 2025). The table ranks every Washington place with 10,000 or more residents by that figure; the IRS column shows net adjusted gross income migration for 2022 to 2023.
| Rank | County | Population | Growth (% per year) | Net domestic migration | Net international migration | IRS net AGI migration |
|---|---|---|---|---|---|---|
| 1 | Clark County | 532,119 | 1.04% | +15,206 | +5,761 | +$291.9M |
| 2 | Spokane County | 558,344 | 0.63% | +10,865 | +4,454 | +$32.7M |
| 3 | Benton County | 221,722 | 1.34% | +7,439 | +3,752 | +$11.2M |
| 4 | Whatcom County | 236,392 | 0.77% | +6,228 | +2,706 | +$71.6M |
| 5 | Lewis County | 88,062 | 1.30% | +5,822 | +611 | +$49.3M |
| 6 | Thurston County | 304,261 | 0.55% | +5,258 | +2,490 | +$82.6M |
| 7 | Mason County | 71,165 | 1.51% | +4,707 | +1,351 | +$44.3M |
| 8 | Cowlitz County | 114,885 | 0.69% | +4,135 | +563 | +$37.6M |
| 9 | Clallam County | 78,202 | 0.22% | +3,987 | +380 | +$82.4M |
| 10 | Kitsap County | 283,374 | 0.54% | +3,638 | +2,651 | +$119.0M |
Go past the headline numbers
The interactive Demographics map layer and the full report for a single place are part of paid plans.
Get the Demographics Report for Lincoln CountyFrequently asked questions
- What are the fastest-growing counties in Washington?
- By population growth from 2020 to 2025, the fastest are Lincoln County (1.86% a year), Douglas County (1.55% a year), Mason County (1.51% a year), Okanogan County (1.42% a year) and Pend Oreille County (1.37% a year) (Census PEP Vintage 2025). Only places with 10,000 or more residents are ranked.
- Where are people moving in Washington?
- By net domestic migration from 2020 to 2025, the largest gains are Clark County (+15,206), Spokane County (+10,865) and Benton County (+7,439) (Census PEP Vintage 2025).
- How fast is Washington growing overall?
- Washington grew 0.70% a year from 2020 to 2025, to 8,001,020 residents, with net migration of +197,729 people (Census PEP Vintage 2025).
- Where does this Washington data come from, and how current is it?
- Population, growth and migration come from the U.S. Census Bureau Population Estimates Program (PEP Vintage 2025 · 2020–2025). Income migration comes from IRS Statistics of Income (IRS SOI 2022–2023 (2-yr lag)). Counties with fewer than 10,000 residents are not ranked (4 of 39 in Washington). Data last loaded 2026-09-23.
Data as of 2026-09-23: sources and periods
- Population, growth and migration
- U.S. Census Bureau, Population Estimates Program: PEP Vintage 2025 · 2020–2025. census.gov/programs-surveys/popest
- Income migration (net AGI)
- Internal Revenue Service, Statistics of Income migration data: IRS SOI 2022–2023 (2-yr lag). irs.gov/statistics/soi-tax-stats-migration-data
How to read the table
- Population is the Census July 1 estimate of the latest vintage.
- Growth is the compound annual rate over 2020 to 2025.
- Net domestic and international migration are cumulative people over 2020 to 2025.
- IRS net AGI migration is adjusted gross income that moved in, less what moved out, for 2022 to 2023. A plus sign means a net inflow.
- Places with fewer than 10,000 residents are left out of the rankings.