Fastest Growing Counties in Idaho (2025)

County
Rank
Change (2020)
2025 Pop.
2020 Pop.
Camas County125.28%1,3581,084
Oneida County217.81%5,3794,566
Canyon County316.4%271,238233,013
Boundary County416.38%14,12712,139
Adams County515.79%5,1274,428
Gem County615.74%22,30519,272
Bonner County715.66%54,82747,403
Jefferson County815.58%35,92231,080
Boise County915.23%8,8317,664
Washington County1013.48%11,98110,558
Franklin County1113.02%16,14214,282
Butte County1211.38%2,8782,584
Idaho County1310.86%18,39616,594
Valley County1410.05%13,03211,842
Lemhi County159.96%8,7557,962
Benewah County169.91%10,5259,576
Clearwater County179.39%9,5728,750
Payette County189.34%27,97925,590
Kootenai County199.07%188,450172,785
Lincoln County208.69%5,5805,134
Fremont County218.46%14,55413,419
Twin Falls County228.25%97,82690,372
Bonneville County238.24%135,012124,737
Power County247.72%8,4877,879
Shoshone County257.64%14,20813,199
Ada County267.57%536,011498,278
Teton County277.45%12,60911,735
Bear Lake County287.4%6,8386,367
Owyhee County297.34%12,87611,996
Jerome County306.92%25,94924,270
Lewis County316.8%3,7673,527
Bingham County326.53%51,23948,097
Minidoka County336.26%23,02421,668
Custer County346.13%4,5334,271
Latah County356.1%42,05539,638
Elmore County366%30,39028,669
Bannock County375.36%91,95087,276
Gooding County384.96%16,42515,649
Cassia County394.2%25,80024,760
Blaine County404%25,32124,348
Caribou County413.48%7,2577,013
Nez Perce County422.37%43,14342,145
Madison County431.51%53,72552,928
Clark County44-1.14%783792

Idaho County Growth Overview

Idaho's counties show varied growth patterns from 2020 to 2025. Camas County leads with 25.28% annualized growth, followed by Oneida County (17.81%) and Canyon County (16.4%). The largest counties are Ada County (536,011), Canyon County (271,238), and Kootenai County (188,450). Of the 44 counties in Idaho, 43 are growing while just 1 has experienced population decline. Overall, counties averaged 9.28% annualized growth, with total population growing by 9.02% annually.