Census release shows most of Idaho’s counties grew in population in 2025
Thirty-six of Idaho’s 44 counties grew in population in 2025, with 20 growing faster than in 2024, according to annual U.S. Census Bureau population estimates. This translates to 80% of Idaho's counties growing in population — much higher than the nation's share of 60%.
Five of Idaho’s urban counties — Ada, Canyon, Kootenai, Bonneville and Twin Falls — added at least 1,000 new residents in 2025. The three most populous counties of Ada, Canyon and Kootenai collectively accounted for more than 75% of the state's annual population growth and over 22,000 new residents.
Annual population growth rates ranged from a low of -1% in Franklin and Fremont counties to a high of 2.9% in Canyon. Ada had the highest total increase of over 10,000 new residents while Blaine had the largest decline of 184.
Figure 1. Top Idaho counties by annual population growth rate, 2024-2025
 Source: U.S. Census Bureau, “Annual Population Estimates, 2020-2025.”
While annual population growth rates of the state’s urban counties held relatively constant between 2024 and 2025 at 1.8%, the rural areas slowed from 1% in 2024 to 0.5% in 2025. As a result, the state’s nine urban counties accounted for 90% of total population growth in 2025.
Of Idaho’s rural counties, eight experienced minor population declines in 2025, resulting in a combined loss of 700 residents. Three counties — Clearwater, Lewis and Elmore — have reported consecutive population declines since 2023.
From 2020-2025, the highest growth rates were in Camas, Canyon and Boundary counties at over 15%. However, the most populated counties of Ada, Canyon and Kootenai had the highest total growth and cumulatively added over 109,000 new residents while comprising 60% of statewide population growth.
Clark — Idaho’s least populated county — was the only county to report a cumulative population decline of 1% (-8 residents) from 2020-2025 and had flat population growth over 2025.
Idaho reported 16 counties with natural population declines (more deaths than births) in 2025 — 15 rural counties and one urban (Nez Perce). Similarly, there were 11 counties — nine rural, two urban — that experienced net migration declines.
No county in Idaho had both natural population and net migration decline simultaneously in 2025.
Population growth of Idaho’s Metropolitan Statistical Areas
More than one out of every five Metropolitan Statistical Areas (MSAs) in the U.S. lost population in 2025, but all six of Idaho’s MSAs experienced population growth.
Combined, Idaho’s six MSAs added over 26,000 new residents in 2025, which was 800 more than 2024. Together, they accounted for 92% of total statewide population growth during 2025.
One-year growth rates ranged from minimal growth in Lewiston to 2.2% in Boise, which had the 13th fastest MSA growth rate nationally and the second fastest in the western U.S. region behind St. George, Utah.
Boise and Coeur d’Alene reported population growth rates that exceeded the statewide rate of 1.4% while Idaho Falls matched it. These MSAs (Boise, Coeur d’Alene, Idaho Falls) all ranked in the top 50 nationally for one-year population growth in 2025.
Figure 2. Idaho MSA annual population estimates, 2024-2025
 Source: U.S. Census Bureau, “Annual Population Estimates, 2020-2025.”
Population growth by labor market region
Nearly two out of every three new residents to the state in 2025 were located within the southwestern region.
Between 2020-2025, the top three regions by growth rate were southwestern, northern and eastern, contributing 80% of Idaho's population growth combined. In 2025 alone, they comprised more than 90% of the state’s population growth.
Three out of every four new residents statewide were a result of in-migration over the past year. Net in-migration accounted for 93% of population growth in northern Idaho and 82% in southwestern. In the north central region, net in-migration accounted for all of the area’s growth and offset a natural population decline.
In contrast, in-migration accounted for less than 50% of total population growth for the south central, southeastern and eastern regions.
Figure 3. Labor market population growth, 2020-2025
 Source: U.S. Census Bureau, “Annual Population Estimates, 2020-2025.”
For more information on U.S. Census Bureau releases, visit census.gov/data.
Past census data for Idaho is available at lmi.idaho.gov/census.
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