Recent population projections from the Idaho Department of Labor anticipate Idaho will continue its record of rapid growth, with the total statewide population crossing over 2 million for the first time by 2031.
The 2020 Census revealed the Gem State was the second-fastest growing state in the nation over the decade from 2010 to 2020, and single-year population estimates have ranked Idaho as the fastest-growing state for the past five years.
Idaho’s Labor Department’s latest projections anticipate a statewide growth rate of 1.1% per year over the 10-year period from 2021 to 2031, adding a total of 227,880 new residents to the state. This will raise Idaho’s population from 1,888,533 in 2021 to 2,116,413 in 2031.
All six of Idaho’s substate regions are expected to grow over the coming decade, with southwestern Idaho leading at 16.3% projected growth, followed by northern Idaho at 13%. These two regions together are expected to account for more than three quarters of the state’s total growth.
TABLE 1: Projected population growth by region
Although all six of Idaho’s regions are projected to grow over the next decade, growth is expected to disproportionately concentrate in southwestern Idaho, specifically the Boise metropolitan statistical area (MSA). The region is projected to grow by 141,391 residents by 2031, accounting for 62% of the state’s total population growth. The region currently accounts for 46% of the state’s total population, but the concentration of growth is expected to raise this to 48% by 2031. This will continue an established trend in Idaho of urbanization and rapid agglomeration in the Boise metro area. In 2001, southwestern Idaho accounted for only 42% of the state’s population but has steadily increased its share over time. Correspondingly, the population in the north central and southeastern regions has declined as a share of the state total. The northern, south central and eastern regions have retained a consistent overall share of the population.
Over the past decade, Idaho has seen significant in-migration of older residents, with disproportionately rapid growth in the 65 and older age groups. That in-migration is expected to continue for the foreseeable future. The 65 and older population statewide is projected to grow by 99,285 by 2031, or 30.7% – substantially faster than the age 15-to-64 population (10.1% projected growth) and the under age 15 population (a 2.5% projected growth). By far the three fastest-growing age cohorts are 85 and older (+73.9%), 80 to 84 (+62.4%) and 75 to 79 (43.4%).
This aging population has significant implications for the structure of growth in the state. As the population ages, the natural growth rate — deaths minus births — declines, both because an older population is expected to have a higher death rate and due to declining births. Over the next 10 years, a majority of Idaho counties are expected to have negative natural growth — more deaths than births. Although 26 counties have negative natural growth projections through 2031, 17 are still projected to experience overall population growth owing to high rates of in-migration.
Overall, most Idaho’s counties are expected to grow through 2031. Thirty-four of the state’s 44 counties have positive growth projections, and 23 counties are expected to grow more than 0.5% per year, which is the annual growth rate of the national population. However, given the continued urbanization of Idaho, it is not surprising that the highest growth projections by far belong to the four largest urban counties — Ada, Bonneville, Canyon and Kootenai. Collectively, these four counties are expected to grow by 177,740 through 2031, accounting for nearly 80% of the state’s growth. As a result, by 2031 more than 72% of Idaho’s population is expected to reside in urban counties, up from roughly 70% in 2021.
Overall, the demographic situation in the United States is in a state of flux. As the baby boomer generation retires, the economy is losing one of the largest and most productive generations of workers ever. At the same time, birth rates continue to steadily decline as millennials form families later in life and have fewer children on average than the generations before them. This has left the country (and by extension individual states) dependent on immigration to sustain population growth. In this environment, Idaho has gained a relative advantage as a desirable state that reliably attracts high in-migration year after year, which has consistently made Idaho one of the fastest-growing and most thriving states in the nation – an advantage that should continue into the foreseeable future.