Idaho is losing too much open space, including farmland, according to a new voter survey and study.

Idaho’s rate of population growth led the U.S. during the past decade and drives development that consumes agricultural ground and other open spaces, said Leon Kolankiewicz, scientific director for NumbersUSA, a nonprofit that advocates for less immigration.

Some 77% of the sprawl in Idaho counties from 1982 to 2017 was related to an increase in the number of residents, he said. A rise in per-capita land consumption drove the rest, referring to the average amount of land occupied by each person.

Large shares of survey respondents saw loss of open space “as a significant adverse effect of that growth, and would prefer much lower or no growth in the future,” said Kolankiewicz, who spoke to the Kootenai-Shoshone County Farm Bureau on Oct. 29.

Population growth contributes to urban sprawl, which continues despite construction of more apartments, condominiums and townhouses, he said.

“The density is higher, but the population growth is so great that it more than offsets it,” driving more sprawl, Kolankiewicz said.

But sprawl is not solely growth-driven. “There are counties with stable or declining populations that have sprawl.”

Potential solutions to sprawl include smart-growth strategies that favor in-fill development within city boundaries as well as high-density housing, and the “more contentious and controversial” idea of controlling U.S. population increases, Kolankiewicz said.

Direct payments or other incentives for farmers and others to stay on working lands, rather than selling to a developer, also have potential to reduce open-space losses, said Rob Harding, a NumbersUSA outreach liaison based in Hayden, Idaho.

The state had just over 1 million residents in 1990 and more than 1.8 million in 2020.

The states losing the most people to Idaho are California, Washington, Oregon, Utah and Arizona.

Demographers expect Idaho’s population, now estimated at 1.9 million, to reach about 2.7 million by 2060 and continue to increase if recent migration and fertility trends continue, he said.

An August survey by NumbersUSA and Rasmussen Reports asked 1,017 likely voters in the state if they found the prospect of adding another 800,000 residents to be more positive or more negative, and 67% said more negative.

Asked about growth since 1990, 47% said they would like Idaho to grow more slowly, while 23% preferred that the population stay about the same and another 23% said they would like it to decrease.

From 1990 to 2019, net migration was responsible for 59% of the population growth, according to the study. The natural increase, reflecting births minus deaths, was 41%.

Idaho growth directly related to international net migration was 8% from 1990 to 2020.

Idaho had 933,400 acres of developed land in 2017, up 66.5% from 560,500 acres in 1982, according to the report, which cited USDA Natural Resources Conservation Service data.

Square miles of sprawl over the period totaled 449 due to increasing population and 134 due to increasing per-capita land consumption, according to NumbersUSA.

Some 48% of voters surveyed said Idaho’s development of open lands into cities, housing and highways was “too much,” and 36% said the level was “about right.” And 81% said protecting American farmland from development is “very important.”