Overview
- COMPASS estimated 847,840 residents in Ada and Canyon counties in 2025, up 24,950—or 3.0%—from its 2024 estimate.
- Canyon County held 32.5% of the two-county population but accounted for 42.2% of the one-year increase.
- The nine Atlas cities accounted for 22,860 of the 24,950-person increase; unincorporated areas and five smaller Canyon County cities account for the remaining 2,090.
- Star, Kuna, Middleton, and Caldwell posted the fastest percentage growth among the nine Atlas cities; Meridian added the most residents in absolute terms.
- Population growth is a demand signal, not proof that a specific project, rent, or resale price will work.
Reported measures
The regional total moved past 847,000
COMPASS estimated 572,020 people in Ada County and 275,820 in Canyon County for 2025. Together, the two counties reached 847,840 residents. The comparable 2024 estimate was 822,890, which means the region added 24,950 people in one year.
That is a 3.0% annual increase. Compared with the 2020 Census totals presented in the same COMPASS series, the two-county region grew by 121,768 residents, or 16.8%, in five years. Those are large additions for a housing system that also has to absorb new roads, utilities, schools, employment space, and public services.
Accounting for the full two-county increase
The nine Atlas cities account for 22,860 people, or 91.6% of the two-county increase. The remaining 2,090 appear in unincorporated Ada County, unincorporated Canyon County, and the five smaller Canyon County cities of Greenleaf, Melba, Notus, Parma, and Wilder.
Star crosses the Ada–Canyon county line, so Atlas combines both county portions for the city total. Percentages are calculated from the published 2024 and 2025 values and rounded to one decimal place.
| Geography | 2024 | 2025 | Change | Change % |
|---|---|---|---|---|
| Boise | 250,060 | 253,550 | +3,490 | +1.4% |
| Meridian | 142,830 | 147,340 | +4,510 | +3.2% |
| Nampa | 119,220 | 123,220 | +4,000 | +3.4% |
| Caldwell | 73,420 | 77,610 | +4,190 | +5.7% |
| Eagle | 37,550 | 38,830 | +1,280 | +3.4% |
| Kuna | 31,490 | 33,750 | +2,260 | +7.2% |
| Star · both counties | 20,370 | 22,370 | +2,000 | +9.8% |
| Garden City | 13,380 | 13,730 | +350 | +2.6% |
| Middleton | 13,190 | 13,970 | +780 | +5.9% |
| Other Canyon cities | 6,130 | 6,160 | +30 | +0.5% |
| Unincorporated Ada County | 62,360 | 63,020 | +660 | +1.1% |
| Unincorporated Canyon County | 52,890 | 54,290 | +1,400 | +2.6% |
| Two-county total | 822,890 | 847,840 | +24,950 | +3.0% |
Fastest percentage growth and largest absolute additions tell different stories
Star had the fastest one-year percentage increase at 9.8% after combining its Ada and Canyon county portions. Kuna followed at 7.2%, Middleton at 5.9%, and Caldwell at 5.7%. Smaller cities can post high percentages on a smaller base, so percentage growth alone should not determine a development or acquisition strategy.
In absolute terms, Meridian added the most residents among the nine cities at 4,510. Caldwell added 4,190, Nampa 4,000, and Boise 3,490. Absolute additions matter for regional demand; percentage change helps expose where the local system is changing fastest. A serious location review needs both.
How to use this in a property decision
Population growth belongs near the top of a market-screening process, not at the end of an underwriting model. It can point to places where housing, retail, transportation, and services may face additional pressure. It cannot establish achievable rent, absorption, resale value, entitlement probability, infrastructure availability, or construction cost for a parcel.
For a project-level decision, this population series should be paired with city planning applications, building permits, parcel records, current inventory, comparable transactions, rent evidence, and a review of the applicable code. The most important next question is not simply whether a city grew. It is whether supply, infrastructure, and the proposed product line up in the specific submarket.
Method and limitations
This brief uses the corrected COMPASS 2025 Historic Population Estimates by City Limits. Atlas calculated one-year differences and percentages from the source table without adjusting the published values. Star is the only Atlas city split between Ada and Canyon counties; its two county components were summed.
COMPASS and the U.S. Census Bureau publish separate estimates using different methods, dates, and revision schedules. Atlas does not splice those vintages into one trend line. When a city page shows a Census figure for a different purpose, the source and period remain visible so the reader can compare like with like.
Methodology
Atlas calculated changes from COMPASS's published 2024 and 2025 city-limit estimates. Star's Ada and Canyon county portions were combined. Values were not blended with a different population-estimate vintage.
Read Atlas methodologySources
- 2025 Historic Population Estimates by City Limits ↗Community Planning Association of Southwest Idaho (COMPASS) · 2025 estimate · Last checked 2026-08-31
These are jurisdiction-boundary estimates. They can differ from Census Population Estimates because the agencies use different methods and vintages.
- Building Permits Survey ↗U.S. Census Bureau · Current release varies by geography · Last checked 2026-08-31
An authorization is not a completed home, and local coverage or reporting lag can vary.