RANKING · 2020 CENSUS · 44 SHOWN OF 44

Largest by population, Idaho counties · 2020

The most populous Idaho counties as of the 2020 population estimates. This list covers the 44 counties in Idaho that qualify, ranked against each other statewide.

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SAME RANKING BYCities States Metros ZIP codes

RELATEDFastest growing Fastest shrinking Most population gained Most population lost Most densely populated Most sparsely populated

YEAR1990 2000 2010 2020 2025

RANKPLACESTATETOTAL POPULATIONVS 2000

01Ada County, IDID494,967+64%

02Canyon County, IDID231,105+76%

03Kootenai County, IDID171,362+58%

04Bonneville County, IDID123,964+50%

05Twin Falls County, IDID90,046+40%

06Bannock County, IDID87,018+15%

07Madison County, IDID52,913+93%

08Bingham County, IDID47,992+15%

09Bonner County, IDID47,110+28%

10Nez Perce County, IDID42,090+13%

11Latah County, IDID39,517+13%

12Jefferson County, IDID30,891+61%

13Elmore County, IDID28,666−2%

14Payette County, IDID25,386+23%

15Cassia County, IDID24,655+15%

16Blaine County, IDID24,272+28%

17Jerome County, IDID24,237+32%

18Minidoka County, IDID21,613+7%

19Gem County, IDID19,123+26%

20Idaho County, IDID16,541+7%

21Gooding County, IDID15,598+10%

22Franklin County, IDID14,194+25%

23Fremont County, IDID13,388+13%

24Shoshone County, IDID13,169−4%

25Boundary County, IDID12,056+22%

26Owyhee County, IDID11,913+12%

27Valley County, IDID11,746+54%

28Teton County, IDID11,630+94%

29Washington County, IDID10,500+5%

30Benewah County, IDID9,530+4%

31Clearwater County, IDID8,734−2%

32Lemhi County, IDID7,974+2%

33Power County, IDID7,878+5%

34Boise County, IDID7,610+14%

35Caribou County, IDID7,027−4%

36Bear Lake County, IDID6,372−1%

37Lincoln County, IDID5,127+27%

38Oneida County, IDID4,564+11%

39Adams County, IDID4,379+26%

40Custer County, IDID4,275−2%

41Lewis County, IDID3,533−6%

42Butte County, IDID2,574−11%

43Camas County, IDID1,077+9%

44Clark County, IDID790−23%

SHOWING 1–44 OF 44

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UPDATED 2026-07-15 · DATA: US CENSUS BUREAU DECENNIAL CENSUS