County facts · Population growth · October 23, 2026
Fastest Growing Counties in Idaho, 2020 to 2025
Idaho's fastest growing counties by percent and by people added, April 2020 to July 2025 Census estimates, with each official parcel map.
Looking for the fastest growing counties in Idaho? From the Census Bureau's April 1, 2020 estimates base to its July 1, 2025 estimate, Idaho went from about 1,839,123 to 2,029,733 residents, a change of +190,610 (+10.4%). The fastest growing county by percentage was Camas County (+22.8%), while Ada County added the most people (+51,175, +10.3%).
Each table links the county's Platbookmapper page and its official parcel viewer, so you can go from the growth numbers straight to the property lines.
Idaho growth at a glance
- County: 44
- Statewide, April 2020 to July 2025: +190,610 residents (+10.4%); July 2024 to July 2025 alone: +28,861 (+1.4%)
- Grew: 43 of 44 · Lost residents: 1
- Fastest growing by percent: Camas County (+22.8%); most people added: Ada County (+51,175)
- Counties with more deaths than births over the period: 17 of 44
The 10 fastest growing Idaho counties by percent
| # | County | Apr 2020 | Jul 2025 | Change | % change | Parcel viewer |
|---|---|---|---|---|---|---|
| 1 | Camas County | 1,072 | 1,316 | +244 | +22.8% | ArcGIS Experience Builder |
| 2 | Canyon County | 231,107 | 275,123 | +44,016 | +19.0% | ArcGIS Web AppBuilder |
| 3 | Boundary County | 12,059 | 13,997 | +1,938 | +16.1% | ArcGIS Experience Builder |
| 4 | Bonner County | 47,114 | 54,420 | +7,306 | +15.5% | county web map |
| 5 | Adams County | 4,378 | 5,013 | +635 | +14.5% | ArcGIS Experience Builder |
| 6 | Jefferson County | 30,891 | 35,297 | +4,406 | +14.3% | Idaho statewide Parcels layer in ArcGIS Map Viewer |
| 7 | Teton County | 11,637 | 13,254 | +1,617 | +13.9% | Idaho statewide Parcels layer in ArcGIS Map Viewer |
| 8 | Gem County | 19,128 | 21,773 | +2,645 | +13.8% | ArcGIS Experience Builder |
| 9 | Boise County | 7,612 | 8,545 | +933 | +12.3% | ArcGIS Experience Builder |
| 10 | Kootenai County | 171,366 | 191,864 | +20,498 | +12.0% | county web map |
These 10 added about 84,238 people combined. The median county changed by +8.3%.
The 10 counties that added the most people
| # | County | People added | % change | Jul 2025 | Parcel viewer |
|---|---|---|---|---|---|
| 1 | Ada County | +51,175 | +10.3% | 546,141 | listed link under review |
| 2 | Canyon County | +44,016 | +19.0% | 275,123 | ArcGIS Web AppBuilder |
| 3 | Kootenai County | +20,498 | +12.0% | 191,864 | county web map |
| 4 | Bonneville County | +11,812 | +9.5% | 135,771 | ArcGIS Experience Builder |
| 5 | Twin Falls County | +7,489 | +8.3% | 97,539 | ArcGIS Experience Builder |
| 6 | Bonner County | +7,306 | +15.5% | 54,420 | county web map |
| 7 | Bannock County | +4,568 | +5.2% | 91,591 | ArcGIS Experience Builder |
| 8 | Jefferson County | +4,406 | +14.3% | 35,297 | Idaho statewide Parcels layer in ArcGIS Map Viewer |
| 9 | Bingham County | +3,166 | +6.6% | 51,153 | Idaho statewide Parcels layer in ArcGIS Map Viewer |
| 10 | Gem County | +2,645 | +13.8% | 21,773 | ArcGIS Experience Builder |
The top 10 account for about 82% of all the gains in the counties that grew.
Where the new residents came from
The Census Bureau splits each change into natural change (births minus deaths), net domestic migration (moves from other parts of the US) and net international migration. Totals for April 2020 to July 2025 in the five fastest growing counties:
| County | Births minus deaths | Net domestic moves | Net international moves | Total change |
|---|---|---|---|---|
| Camas County | +41 | +167 | +42 | +244 |
| Canyon County | +7,100 | +32,799 | +4,389 | +44,016 |
| Boundary County | −17 | +1,791 | +168 | +1,938 |
| Bonner County | −519 | +7,600 | +293 | +7,306 |
| Adams County | −81 | +711 | +16 | +635 |
In all 5, moves from elsewhere in the US were the biggest source of growth. The three parts do not add up exactly to the total because the Census Bureau also carries a small residual.
The last year alone: July 2024 to July 2025
- Canyon County: +2.9% (+7,679)
- Camas County: +2.3% (+29)
- Butte County: +2.1% (+57)
- Ada County: +2.0% (+10,916)
- Kootenai County: +1.8% (+3,466)
3 of these 5 are also in the 2020–2025 top 10, so the growth is not a one-year blip.
Counties losing residents
1 of Idaho's 44 counties had fewer residents in July 2025 than in April 2020. It is:
- Clark County: −0.6% (−5, now about 783)
What fast growth means on a parcel map
- New lots show up as plats first. When land is subdivided, the plat is recorded with the county and the parcel layer catches up on its own schedule, so a brand-new lot may not appear on the map for a while. Check the recorder's recent plats if a parcel looks missing.
- Parcel numbers change after splits. A tract that was one parcel last year can be several today. Search by owner name or address as well as by an old parcel number.
- City limits move. Growing cities annex land, which changes who handles zoning and permits even though the county still keeps the deed and the tax map.
- Percent is not the same as people. A small county can post a big percentage on a modest number of new residents, so read the people-added column too.
Related guides
- Largest counties in Idaho
- Idaho county GIS websites by viewer
- Idaho landowner maps for hunting
- Fastest growing counties in the US
- US counties losing population
More: All Idaho counties on Platbookmapper
Sources
- U.S. Census Bureau, Population Estimates Program, county totals, Vintage 2025 (April 1, 2020 estimates base and July 1, 2020–2025 estimates, with components of change). Percent change is from the April 1, 2020 estimates base to the July 1, 2025 estimate.
- Platbookmapper county GIS directory (live data file behind our county pages, pulled October 23, 2026) for each official parcel viewer.