36 of Idaho’s 44 counties grew in 2025. Here’s where it’s happening fastest

The Treasure Valley grew by more than 50 people a day in 2025 as Ada and Canyon counties continued to buoy Idaho’s population boom.

Idaho’s six urban counties paced a statewide 1.4% increase last year, bringing Idaho’s population close to 2.03 million, according to U.S. Census Bureau data compiled by the Idaho Department of Labor. That’s good for second in the nation, trailing South Carolina by one-tenth of a percentage point.

The Boise Metropolitan Statistical Area — Ada, Canyon, Boise, Gem and Owyhee counties — propelled much of the expansion. Growing at 2.2%, the Boise area was the 13th fastest growing market in the country and the second fastest in the West, trailing just St. George, Utah, according to the report. The Coeur d’Alene and Idaho Falls metropolitan statistical areas joined Boise in the top 50 of America’s fastest growing nationwide cities.

Canyon County, meanwhile, more than doubled the state’s growth rate, growing by 2.9% — 7,679 people — to reach a total of 275,125. Ada County, far and away Idaho’s largest at nearly 550,000 residents, added 10,916 people, a 2% boost. Taken together the two counties account for more than 40% of Idaho’s population, and two of every three new residents settled in the state’s southwest, according to the Department of Labor.

Idaho cities propel population growth

Growth in 2025 was primarily urban, with more than 75% of the state’s 28,861 residents flocking to Idaho’s three largest counties: Ada, Canyon and Kootenai, which includes Coeur d’Alene and Post Falls. Since 2020, 109,000 people moved into these three counties, accounting for 60% of the state’s unceasing growth.

New residents continued to coalesce in larger counties last year. Idaho’s nine largest counties absorbed 90% of new residents in 2025, according to the Department of Labor.

The same can’t be said for every American city, or every Idaho county. One in five metropolitan areas lost people in 2025, according to Census data. And eight of Idaho’s 44 counties — mostly smaller, rural jurisdictions — saw declines.

But the story here is still one of growth. Eighty percent of Idaho counties saw their population increase in 2025, and 45% grew faster than the year prior, according to the report. The main reason: migration. Residents moving from out of state accounted for 93% of population growth in northern Idaho and 82% of in southwestern Idaho.

Idaho still popular with out-of-state movers

None of this is surprising to the moving industry. Both United and Atlas van lines both ranked Idaho as one of the most popular states to move to in 2025 based on the ratio of bookings into or out of a state. United ranked the Gem State sixth, while Atlas placed it second, with close to twice as many trips heading into the state as leaving — the highest ratio since 2020.

Neither study specified where new Idahoans were coming from. But research from ApartmentList.com, a rental clearinghouse, found that 25% of people looking to relocate to Boise were around Seattle, and 20% were in Salt Lake City. No other metropolitan area topped 3%.

The net effect is a state that’s growing much faster than the nation at large. Since 2020, Idaho’s population has grown nearly 10%, more than three times the national average. Go back 20 years, and it has grown by 42%, compared with 15.7% nationwide.