RANKING · 2025 ESTIMATES · 44 SHOWN OF 44

Most densely populated, Idaho counties

Idaho counties ranked by residents per square mile (2025). This list covers the 44 counties in Idaho that qualify, ranked against each other statewide. The median across all 44 is 10.

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SAME RANKING BYCities States Metros

RELATEDLargest by population Fastest growing Fastest shrinking Most population gained Most population lost Most sparsely populated

YEAR1990 2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION DENSITYVS 2000

01Ada County, IDID546,141519+82%

02Canyon County, IDID275,123469+109%

03Kootenai County, IDID191,864155+77%

04Madison County, IDID55,172118+101%

05Bannock County, IDID91,59182+21%

06Bonneville County, IDID135,77173+65%

07Payette County, IDID27,82468+35%

08▲1Twin Falls County, IDID97,53951+52%

09▼1Nez Perce County, IDID42,90551+15%

10Jerome County, IDID26,36244+44%

11▲1Gem County, IDID21,77339+43%

12▼1Latah County, IDID41,84239+20%

13▲1Jefferson County, IDID35,29732+84%

14▲1Bonner County, IDID54,42031+48%

15▼2Minidoka County, IDID22,91130+14%

16Teton County, IDID13,25430+121%

17Bingham County, IDID51,15324+23%

18Franklin County, IDID15,88924+40%

19Gooding County, IDID16,44623+16%

20Benewah County, IDID10,50814+15%

21▲1Boundary County, IDID13,99711+42%

22▼1Cassia County, IDID26,39710+23%

23▲1Blaine County, IDID25,51710+34%

24▼1Elmore County, IDID29,46510+1%

25▲1Washington County, IDID11,5838+16%

26▼1Lewis County, IDID3,7048−1%

27Fremont County, IDID14,2088+20%

28Bear Lake County, IDID6,7277+5%

29Power County, IDID8,2466+9%

30Shoshone County, IDID14,1305+3%

31Lincoln County, IDID5,6035+39%

32Boise County, IDID8,5454+28%

33▲1Oneida County, IDID5,0854+23%

34▼1Caribou County, IDID7,2524−1%

35Clearwater County, IDID9,1184+2%

36Adams County, IDID5,0134+44%

37Valley County, IDID12,8314+68%

38Idaho County, IDID17,8742+15%

39Lemhi County, IDID8,4742+9%

40Owyhee County, IDID12,6612+19%

41Butte County, IDID2,7831−4%

42Camas County, IDID1,3161+33%

43Custer County, IDID4,6361+7%

44Clark County, IDID7830−23%

SHOWING 1–44 OF 44

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UPDATED 2026-09-11 · DATA: US CENSUS BUREAU POPULATION ESTIMATES