In-Migration Accounted for 73 Percent of Idaho’s Population Increase
Idaho’s population continued to become more urbanized from mid-2017 to mid-2018, with nearly 73 percent of the growth coming from outside the state, newly released data from the U.S. Census Bureau shows. The data provides additional detail at the county level to the January release that showed Idaho’s 2.1 percent population increase tied with Nevada as the fastest-growing state in the nation.
The Boise Metropolitan Statistical Area (MSA) population grew by 2.9 percent – the eighth fastest among the nation’s 383 other MSAs. The five counties that comprise the Boise MSA – Ada, Boise, Canyon, Gem and Owyhee counties – increased by 20,346 people accounting for 58 percent of the state’s total increase of 35,304. The concentration of more than half of Idaho’s growth in the Boise MSA typifies the continued steady shift toward urbanization of the state’s population from rural to urban counties.
Looking at the all of Idaho’s counties, the Idaho Department of Labor divides the state up into six regions (see tables and map). Within each region except for the north-central region (Region II), there is at least one urban county.
The six Idaho counties the U.S. Census Bureau identifies as urban – Ada, Bannock, Bonneville, Canyon, Kootenai and Twin Falls – accounted for more than 80 percent of the state’s population increase at 28,191 additional people in 2018 over 2017. Seventy percent of the population increase in Idaho’s urban counties occurred in Ada and Canyon counties. Kootenai County accumulated 4,020 additional people accounting for about 14 percent of the total increase in urban counties.
The remaining 20 percent of the annual population growth, an increase of 7,113 people, nearly was evenly dispersed across Idaho’s 38 rural counties. Southwestern Idaho grew the fastest with an increase of 16.3 percent and claimed more than 28 percent of the total population increase among all of Idaho’s rural counties. Northern Idaho’s 5.4 percent growth was fifth fastest among Idaho’s regions, but was more than 20 percent of the total change for rural Idaho, second largest after southwestern Idaho.
These differences in the rates and quantities of growth between Idaho’s rural and urban counties from 2017 to 2018 indicate Idaho has shifted toward increased urbanization by 0.3 percent.
Southwestern Idaho is the most urbanized with 86 percent of is population concentrated in Ada and Canyon counties, and 14 percent in the eight other southwestern counties that include Adams, Boise, Elmore, Gem, Owyhee, Payette, Valley and Washington. However, the rate of urbanization was fastest in the eastern half of Idaho, with the population in Bannock and Bonneville counties absorbing 0.2 percent more of the population than the rural counties in their respective regions.
Components of Population Change
The 35,304 increase in Idaho’s total population brought its 2018 level to 1,754,208. About 27 percent – or 9,423 – of this increase was from natural population increase (births minus deaths).
The estimated number of Idahoans who moved to Idaho between July 1, 2017, and July 1, 2018, was 25,776, and accounted for 1.5 percent of the state’s total population.
More people moved into 35 of Idaho’s 44 counties than moved out. The increase from net migration ranged from 11,056 in Ada County to just one in Bear Lake County. Nine counties – Butte, Lincoln, Fremont, Cassia, Clark Lewis, Gooding, Minidoka and Madison – experienced losses in net migration with 1,355 more people leaving than moving in. The 13 counties that make up Idaho’s six MSAs accounted for 90.5 percent of the state’s net migration.
County specific highlights include:
- Boise County had the highest percentage gain in population of all Idaho counties from July 2017 to July 2018 while the numeric gain was centered in six urban counties – Ada, Canyon, Kootenai, Bonneville, Bannock and Twin Falls.
- Idaho had four counties with a population of 10,000 or more that ranked nationally in the top 100 in percentage growth – Jefferson and Valley (3.3 percent), Canyon (3.1 percent) and Bonner (2.5 percent).
- Ten counties had a percent increase larger than the state’s 2.1 percent gain. Forty‐one counties showed population increases ranging from 13,081 people in Ada County to 11 additional people in Butte County. Six counties reported growth in excess of 1,000 – Ada (13,081), Canyon (6,628), Kootenai (4,020), Bonneville (2,162), Bannock (1,497) and Bonner (1,106).
- Three counties experienced a decrease in population – Clark’s population decreased by 33, Lewis’ population dropped by 41 and Madison’s dropped by 69.
- Clark County experienced the smallest number of births at six with the fewest deaths at three. Three Idaho counties had a natural increase of more than 1,000 – Ada (1,968), Canyon (1,630) and Bonneville (1,053). Seven counties experienced net losses – Lewis (2), Bonner (4), Benewah (9), Idaho (13), Lemhi (17), Clearwater (28) and Shoshone (35).
Nationally, the Census Bureau noted that the South and West regions of the U.S. led the nation in population growth. As the following map indicates, Idaho’s growth is a pattern of a new western migration.