Two smaller Ada County communities are experiencing explosive population growth that far outpaces the region’s larger cities, according to new estimates from the Community Planning Association of Southwest Idaho.
Star and Kuna both recorded double-digit percentage increases in population between 2025 and 2026, with Star growing by 23.6 percent and Kuna expanding by 14.3 percent during that period.
Star’s Dramatic Expansion
Star, which sits across both Ada and Canyon counties, saw its population jump from 22,370 residents to 27,660 in just one year. The majority of Star’s residents live on the Ada County side, but the town’s Canyon County population has surged from just 10 people in 2021 to 710 this year.
New subdivisions are under development on the north side of Star, and State Street now features numerous recently opened businesses alongside construction projects still in progress.
Kuna’s Strong Growth
South of Star, Kuna added nearly 5,000 residents over the past year, growing from 33,750 to 38,560 people. That represents a 14.3 percent increase year over year.
Middleton also posted significant gains at 8.8 percent growth, climbing from 13,970 residents to 15,110.
How Larger Cities Compare
By contrast, Idaho’s three most populous cities grew at much slower rates. Boise, Meridian, and Nampa averaged just 2.4 percent growth during the same period.
Meridian grew by 3.2 percent, while Boise recorded only 1.1 percent growth. Caldwell led the larger cities with 6.6 percent growth.
In terms of raw numbers rather than percentages, Caldwell and Meridian added the most new residents, gaining 5,160 and 4,730 people respectively.
Regional Population Trends
COMPASS updates its population estimates each April 1 using the most recent Census count as a baseline. The organization then factors in local building permits, current household sizes, vacancy rates, and recent annexations to calculate growth.
Ada County’s population now stands at an estimated 589,500, while Canyon County has reached 287,260. Together, the two counties total 876,760 residents.
That combined figure was 847,840 last year, 726,072 in 2020, and 581,298 in 2010. The two-county region is steadily approaching the 1 million population milestone.
When Boise and Elmore counties are included in the calculations, the four-county total reaches 915,940 residents.
Planning for Continued Growth
Austin Miller, planning team lead at COMPASS, said the data reveals important patterns about regional development.
According to a statement released by the organization, the growth percentages in smaller communities are particularly striking and underscore the need for multiple analytical approaches when examining population trends.
Miller noted that numeric growth, percent growth, year-over-year changes, and comparisons to Census counts each provide different insights into how the region is expanding. These varied perspectives help COMPASS and individual jurisdictions plan for future infrastructure and service needs.
Impact on Ada County Communities
The rapid growth in Star and Kuna presents both opportunities and challenges for these traditionally rural communities. With populations swelling by thousands of residents in a single year, both towns face increased demands for schools, roads, water infrastructure, and public services.
New commercial development along major corridors suggests businesses are following the residential growth, bringing retail and service options closer to where people live.
Property owners in these fast-growing areas have seen significant increases in home values as demand for housing continues to outpace supply throughout Ada County and the broader Treasure Valley.
What the Data Shows
The full COMPASS population report provides detailed breakdowns for all communities in the four-county region. The report is available to the public at compassidaho.org.
The data shows that while Boise and Meridian remain the region’s population centers, the future growth trajectory is shifting toward smaller communities on the urban fringe. Star and Kuna are positioned at the leading edge of this expansion pattern that has characterized Treasure Valley development for the past two decades.
For Ada County residents, these numbers confirm what many have observed firsthand: the county’s smaller towns are transforming from rural agricultural communities into suburban residential centers at a pace that few could have predicted even five years ago.