It’s not just growth. Idaho is also losing residents and changing fast.

He kept hearing and reading the same claim: Californians were moving to Idaho. Some claimed the newcomers were changing the state and bringing cash to buy homes for astronomical prices.

But University of Idaho professor Jaap Vos wanted to know if it was true. So, he looked for the data. He settled on a mix of data from the Idaho Transportation Department and the U.S. Census Bureau — painting a picture of migration into and out of Idaho.

What he found was not just a rapidly and steadily growing population — and, yes, many newcomers from California — but a huge amount of demographic change in recent years.

Idaho is growing. Under that growth is perhaps a more interesting story, Vos says: The departure of thousands of Idahoans, replaced by residents from other states.

Vos found that, on an average day in 2021, 180 people moved into Idaho and 137 moved out of state.

Why does it matter where someone is ‘from’?

Vos is a professor of planning and natural resources at the university in Moscow. He specializes in research related to rural communities. Just like urban cities like Boise, small rural communities are affected by migration and demographic changes.

“The reason I started doing this was because we really didn’t know what was happening in rural communities,” he said. “We heard all of these stories, but what was really going on?”

Vos hopes to turn this one-time research project into a regular thing — an annual or semiannual report on Idaho population change. Looking at demographic change, in addition to sheer growth, could help community planners, he said.

Any place will change when it loses longtime residents, and more than replaces them with transplants. In Idaho, that shift happened rapidly in the past decade, Vos said.

Such rapid change can affect Idaho’s commerce, politics, economy, housing and job market.

New Idahoans might have a different source of income, different professions and education levels, and different spending power, he said.

They might have moved here to live, but participate less in the local economy — if they work a remote job and prefer to shop on Amazon instead of at local stores, for example. They may not be loyal to Idaho’s small, family owned businesses — or, they could bring with them a strong “shop local” consumer philosophy. And, Vos noted with a laugh, they might not be a University of Idaho Vandal but instead root for Caltech. They might even have different driving habits.

“Somebody who comes here, do they go to the local store, or do they go to a (chain store) they know from where they came from?” he said.

Vos found that nearly half a million of Idaho’s 1.84 million residents are new to the state in the past decade.

He used a mix of census and Idaho Transportation Department data to get a rough idea of the movement into and out of Idaho, down to the county level. It’s not an exact science, he acknowledged.

He said the Boise area — mainly Ada County — attracted people from California’s major urban areas. Coeur d’Alene attracted people from northern California and Washington, and Pocatello and Idaho Falls attracted people from Utah.

But the most important finding was how many residents are leaving the state.

“We need to stop looking at just growth,” he said. “Why are people moving out? … What is causing that? Is it because housing wasn’t affordable? Is it because of the economy? It’s not clear.”