What are the fastest-growing counties in Idaho?
Canyon County is the fastest-growing county in Idaho: its population grew 3.38% a year from 2020 to 2025, to 275,123 residents (Census PEP Vintage 2025). Boundary County (2.89%) and Bonner County (2.80%) follow. Idaho as a whole grew 1.88% a year to 2,029,733 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 Idaho by population growth, 2020 to 2025
| Rank | County | Population | Growth (% per year) | Net domestic migration | Net international migration | IRS net AGI migration |
|---|---|---|---|---|---|---|
| 1 | Canyon County | 275,123 | 3.38% | +31,228 | +4,379 | +$184.7M |
| 2 | Boundary County | 13,997 | 2.89% | +1,709 | +168 | +$12.4M |
| 3 | Bonner County | 54,420 | 2.80% | +7,268 | +293 | +$67.3M |
| 4 | Jefferson County | 35,297 | 2.58% | +2,950 | +235 | +$25.8M |
| 5 | Gem County | 21,773 | 2.47% | +2,050 | +757 | +$20.2M |
| 6 | Teton County | 13,254 | 2.46% | +799 | +330 | +$25.5M |
| 7 | Franklin County | 15,889 | 2.15% | +1,091 | +58 | +$5.4M |
| 8 | Kootenai County | 191,864 | 2.12% | +18,599 | -138 | +$153.1M |
| 9 | Benewah County | 10,508 | 1.87% | +1,124 | +18 | +$4.2M |
| 10 | Washington County | 11,583 | 1.87% | +1,072 | +276 | +$6.1M |
Where are people moving in Idaho?
Ada County gained the most people from elsewhere in the United States: net domestic migration of +35,565 from 2020 to 2025 (Census PEP Vintage 2025). The table ranks every Idaho 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 | Ada County | 546,141 | 1.85% | +35,565 | +6,943 | +$326.2M |
| 2 | Canyon County | 275,123 | 3.38% | +31,228 | +4,379 | +$184.7M |
| 3 | Kootenai County | 191,864 | 2.12% | +18,599 | -138 | +$153.1M |
| 4 | Bonner County | 54,420 | 2.80% | +7,268 | +293 | +$67.3M |
| 5 | Bonneville County | 135,771 | 1.71% | +6,851 | +633 | +$22.9M |
| 6 | Twin Falls County | 97,539 | 1.54% | +5,118 | +1,264 | +$29.8M |
| 7 | Jefferson County | 35,297 | 2.58% | +2,950 | +235 | +$25.8M |
| 8 | Bannock County | 91,591 | 0.97% | +2,556 | +767 | +$0.2M |
| 9 | Payette County | 27,824 | 1.70% | +2,099 | +50 | +$13.1M |
| 10 | Gem County | 21,773 | 2.47% | +2,050 | +757 | +$20.2M |
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 Canyon CountyFrequently asked questions
- What are the fastest-growing counties in Idaho?
- By population growth from 2020 to 2025, the fastest are Canyon County (3.38% a year), Boundary County (2.89% a year), Bonner County (2.80% a year), Jefferson County (2.58% a year) and Gem County (2.47% a year) (Census PEP Vintage 2025). Only places with 10,000 or more residents are ranked.
- Where are people moving in Idaho?
- By net domestic migration from 2020 to 2025, the largest gains are Ada County (+35,565), Canyon County (+31,228) and Kootenai County (+18,599) (Census PEP Vintage 2025).
- How fast is Idaho growing overall?
- Idaho grew 1.88% a year from 2020 to 2025, to 2,029,733 residents, with net migration of +155,060 people (Census PEP Vintage 2025).
- Where does this Idaho 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 (14 of 44 in Idaho). 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.