MERIDIAN, Idaho — The Community Planning Association of Southwest Idaho (COMPASS) estimates that the population in Southwest Idaho has grown by roughly 150,000 since the last census was taken in 2020.
A COMPASS 2026 Population Estimate states that the combined population of Ada, Canyon, Boise, and Elmore Counties is now 915,940. Each April, COMPASS updates its population estimates "using local building construction permits, current household sizes and vacancy rates, and recent annexations (expansions of city limits)."
COMPASS concedes that not all the same data sets are available across counties, so they adapt their models based on the data available to accurately predict population growth.
“While our population growth is spread throughout the region, the percentage of growth in some of our smaller communities is staggering,” explains COMPASS Planning Team Lead Austin Miller. “For example, the Cities of Kuna and Star each grew by 14% in just one year, as compared to larger cities, such as Meridian and Nampa, which each grew by 3% in the same period."
Other findings from the COMPASS estimate indicate that Ada, Boise, Canyon, and Elmore Counties' combined population has surged by 20% since the previous census.
Star topped all urban centers with an estimated 131% population growth.
Meanwhile, Caldwell gained the most people, with an estimated 5,160 new residents moving to the city over the past six years. Meridian and Kuna were just behind Caldwell in terms of population growth.
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To put things in historical perspective, Ada County, which is Idaho's most populous county, has grown from 392,385 in 2010 to 589,500 in 2026, a 50% increase. In 1990, the Ada County population was just 205,775.
You can find COMPASS' entire 2026 population estimates below.
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