Executive Summary

Population Growth & Sprawl Come to the Northern Rockies

Idaho remains the relatively sparsely-populated, agricultural and natural wonderland that residents love. But those qualities are threatened by Idaho’s fastest population growth rate in the country over the last decade – growth that most Idahoans want to slow down or stop, according to a poll commissioned for this study. 

Driving most of the rapid population growth are people moving from much more densely populated countries and states (especially California) to enjoy in Idaho what their home areas are losing or have already lost.

  • More than 370,000 acres of Idaho farmland and natural habitat were lost to development between 1982 and 2017 (latest data from the U.S. Department of Agriculture’s National Resources Inventory).

  • Cropland – Idaho’s most valuable farmland – was reduced by 16% (1982-2017).

  • The state’s population nearly doubled (1980-2020), surging by almost 900,000 people to a total of 1.8 million. Present trends suggest the population may grow by that much again by 2050.

  • Our study finds that 77% of the farmland and habitat loss (1982-2017) was related to accommodating Idaho’s increased population.

  • The other 23% of loss was related to all other factors that led to increased average developed-land consumption for each resident (per capita sprawl).

Trends for the future

As this study shows, trends can be changed. Idaho voters can choose to accept the trends or to mitigate them. They can decide how much agricultural land they are ultimately willing to sacrifice to population growth, as well as how much increased density of living they are willing to accept.

Polling of Idaho voters in August 2023 in conjunction with our study found nearly all wanting to at least slow down the recent rate of population growth.

47% 23% 23% 5% wanted to slow down the growth preferred to stop growth and stay the current population size desired a reduction in the current size wanted to continue to grow rapidly

The state’s overall vital signs remain healthy enough that it has room to preserve much of what its voters say they value. But this study finds current trends are in the wrong direction for preservation, with little indication of government entities acting to change the trends. For example:

  • The American Farmland Trust projects that more than 100,000 additional acres of Idaho’s agricultural land will be lost by 2040 under current trends and policies.

  • By 2050, based on recent rates of development, approximately 180,000 more acres of Idaho’s irreplaceable rural lands of all kinds will have been paved or covered with additional subdivisions, streets, hotels, schools, and commercial strips; industrial, office and theme parks;  places of employment, leisure, culture and waste disposal – all a great and permanent loss to Idaho’s agricultural lands, wildlife habitat, natural heritage, quality of life, and environmental sustainability.

Our poll of 1,017 Idaho likely voters found strong support for their state’s agricultural industry which is the nation’s No. 1 producer of potatoes, barley, peppermint, and alfalfa hay; the No. 2 producer of sugar beets and hops; and the No. 3 producer of cheese and milk, as well as a significant source of more than a hundred other products.

73% oppose diverting water from agricultural irrigation to handle more residents (only 12% support).

81% said it is “very important” to “protect U.S. farmland from development so the United States is able to produce enough food to feed Americans in the future” (14% said “somewhat important” and 3% said not very or at all important.).

Idaho’s fate tied to California’s?

Perhaps the greatest pressure on Idaho’s future comes from California having apparently reached some kind of tipping point after a century of massive population expansion to nearly 40 million residents – 20 times the size of Idaho. Since 1982, more than 2 million acres of California have been converted from farmland and natural habitat to developed land while the population boomed.

People fleeing California’s extensively documented and heavily publicized socioeconomic and environmental problems – particularly the high cost of housing – are the largest single source of Idaho newcomers. 

Idaho, with its population density of 23 residents per square mile, can look awfully alluring to Californians living at a density of 258 residents per square mile and seeking more elbow room and lower housing prices. As high levels of foreign immigration continued into California in the last decade, nearly 8 million Americans moved from California to other states from 2010 through 2021.

Even a tiny fraction of disgruntled Californians spilling into Idaho can swamp efforts to preserve the state’s character and elbow room. Thus, Idaho’s future appears inextricably linked to the fate of California, a state that Idaho residents overwhelmingly say they don’t want to emulate.  Bumper stickers and other signs with slogans such as  “Don’t Californicate Idaho” attest to the fear.

Sources of Idaho population growth

Net migration from other states and countries (new residents minus those leaving)  accounted for 59% of Idaho’s population growth from 1990 to 2020. The impact is even higher than the 59% because of births to those newcomers after they arrive, but data are not available to quantify that.

The states sending the most new residents to Idaho have been California, Washington, Oregon, Utah, Arizona, and Texas, all of which have themselves grown rapidly in recent decades, though that can change year-over-year.

Data do exist to determine the full population impact of foreign-born newcomers to Idaho. The Idaho residents in 2017 who arrived in the U.S. as immigrants after 1982, or who were the U.S.-born children and grandchildren of post-1982 immigrants, were equal to 18% of Idaho’s population growth 1982-2017

Even that calculation understates the role of federal immigration policies in Idaho’s rapid population growth. As noted in the discussion of California, problems from population pressures play a significant role in driving so many Americans from the prime-sending states to Idaho. And the population growth in those states is heavily fueled by federal immigration policies that have more than tripled annual national admissions over their 1960s levels.  

  • California, for example, has for decades tried to absorb around a quarter of the nation’s annual immigration. In the process, it has ceased to be a net desired destination for Americans in the rest of the country. 

  • In every year but 1999 and 2000 over the last three decades, more Americans have moved out of California than have moved in. The net out-migration has routinely been between 100,000 and 300,000 a year. Last year, it was more than 400,000.

  • When considering a continuation of current state trends and federal immigration policies, California analysts project that the state will continue to shed large numbers of residents for at least several more decades

  • Because California’s population growth has been overwhelmingly due to foreign immigration, much of California’s hemorrhaging into Idaho and other western states must be considered as another consequence of the more than tripled level of annual federal immigration.

Preferences of Idaho voters

Opinion polls, at best, can only capture a snapshot of public sentiment. In Idaho, that snapshot reveals that voters in the state oppose the continuation of recent rapid growth.  If a concerted public debate emerges, voters may modify those opinions.  The percentage of “not sure” answers on some questions indicates that many voters may not have thought much about the issues. And voter opinions don’t easily translate into action; politicians and influential business leaders often take the position that more growth is always good. But most Idaho voters who were polled felt differently. 

Only 11% of voters said Idaho’s recent development of farmland and natural habitat has been “too little.”  About a third (36%) indicated that the amount of development is “about right,” while nearly half (48%) said there has been “too much” development already.

Voters reacted even more negatively to the idea of more population growth.

A study of government data found that three-quarters (77%) of the loss of Idaho’s open space, natural habitat, and farmland to development in recent decades was related to the state's rapid population growth. Would continuing this level of population growth into the future make Idaho better, worse or not much different? A study of government data found that three-quarters (77%) of the loss of Idaho’s open space, natural habitat, and farmland to development in recent decades was related to the state's rapid population growth. Would continuing this level of population growth into the future make Idaho better, worse or not much different?

77% 12% 7% worse not much different better

Other survey questions revealed what changes Idaho voters would support to reduce the state’s population growth. They indicated a strong preference for reducing federal immigration and for restricting development to make it more difficult to move into Idaho from other states:

A major source of Idaho’s population growth is people moving in from other states, especially places like California. Should local and state governments in Idaho make it more difficult for people to move to Idaho from other states by restricting development?

56% 27% 18% yes no not sure

One potential way of controlling new growth is by limiting the number of new hook-ups to sewage lines and wastewater treatment plants. Do you favor using this as a tool to manage or control growth?

52% 26% 22% yes no not sure

Another major source of Idaho population growth is immigration from other countries. Should the federal government reduce annual immigration to slow down Idaho’s population growth, keep immigration and population growth at the current level, or increase annual immigration and population growth?

54% 31% 8% 7% reduce annual immigration keep immigration at it's current level increase immigration not sure

Forcing more density in housing development to mitigate the damage of population growth had fairly strong support but was still opposed by 47% to 42%.

One way for Idaho communities to handle continued population growth without losing as much open space, natural habitat, and farmland is to change zoning and other regulations to funnel more current and future residents into apartments and condo buildings instead of single-family houses with yards. Do you strongly favor that change, somewhat favor it, somewhat oppose it or strongly oppose it?

27% 24% 23% 15% 12% somewhat favor somewhat oppose strongly oppose strongly favor not sure

Idaho voters had no interest in sharing the additional costs of accommodating population growth:

Residential development (building subdivisions) to perpetually accommodate new population growth imposes economic costs on the existing residents of municipalities. Do you favor paying higher property taxes to perpetually accommodate new residents in your community?

79% 11% 10% no not sure yes

If Idaho is to avoid “Californication,” there are real, substantial actions that will have to be taken. Without remedial action, the population pressures from other states noted above appear certain to continue to make Idaho less agricultural and filled with more urban sprawl. That sprawl in 21st Century America is predictable – strip malls, fast food restaurants, big-box retail stores, more congestion, high-density subdivisions, and rustic, low-density dwellings chewing into the remaining countryside. As unique as Idaho is in its natural splendor, its settlements will expand the same way as other growing urban areas, by eliminating farmland and natural habitat. 

Combating urban sprawl begins with the simple acknowledgement that it is occurring and then taking a stand against its continuance.  It is easy to succumb to the notion that growth is inevitable or preordained, that it is synonymous with “progress.” However, a clear-headed approach recognizes the trade-offs and considers whether those trade-offs are worth it.

Not taking the environment for granted

Idaho contains about 32 million acres (50,000 square miles) of federally-owned public lands, comprising more than 60 percent of the state. That is a lot of nature and open space. It would be easy to take it for granted. But this study examines facets of Idaho’s swelling human numbers that over the next decades could negatively change Idahoans’ access to wildlands and the quality of the outdoor recreational experience, water availability, wildlife, the ecological footprint, and economic and environmental sustainability.

With the projected population growth both in Idaho (from 1.9 million in 2023 to a projected 2.7 million by 2060) and surrounding states and the country as a whole, increasing pressures on Idaho’s wildlands are to be expected, both from increasing recreational demand itself, and demands for natural resource commodities (forest products, minerals, etc.) from those lands in public ownership.  Opportunities for solitude in Idaho’s wilds will decrease accordingly.