RANKING · 2020 CENSUS · 44 SHOWN OF 44

Most densely populated, Idaho counties · 2020

Idaho counties ranked by residents per square mile (2020). This list covers the 44 counties in Idaho that qualify, ranked against each other statewide. The median across all 44 is 10.

Flip the list · Most sparsely populated, US counties →

IdahoAll states All rankings

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, IDID546,141470+64%

02Canyon County, IDID275,123394+76%

03Kootenai County, IDID191,864138+58%

04Madison County, IDID55,172113+93%

05Bannock County, IDID91,59178+15%

06Bonneville County, IDID135,77166+50%

07Payette County, IDID27,82462+23%

08Nez Perce County, IDID42,90550+13%

09Twin Falls County, IDID97,53947+40%

10Jerome County, IDID26,36241+32%

11Latah County, IDID41,84237+13%

12Gem County, IDID21,77334+26%

13Minidoka County, IDID22,91129+7%

14Jefferson County, IDID35,29728+61%

15Bonner County, IDID54,42027+28%

16Teton County, IDID13,25426+94%

17Bingham County, IDID51,15323+15%

18Franklin County, IDID15,88921+25%

19Gooding County, IDID16,44621+10%

20Benewah County, IDID10,50812+4%

21Cassia County, IDID26,39710+15%

22Boundary County, IDID13,99710+22%

23Elmore County, IDID29,4659−2%

24Blaine County, IDID25,5179+28%

25Lewis County, IDID3,7047−6%

26Washington County, IDID11,5837+5%

27Fremont County, IDID14,2087+13%

28Bear Lake County, IDID6,7277−1%

29Power County, IDID8,2466+5%

30Shoshone County, IDID14,1305−4%

31Lincoln County, IDID5,6034+27%

32Boise County, IDID8,5454+14%

33Caribou County, IDID7,2524−4%

34Oneida County, IDID5,0854+11%

35Clearwater County, IDID9,1184−2%

36Adams County, IDID5,0133+26%

37Valley County, IDID12,8313+54%

38Idaho County, IDID17,8742+7%

39Lemhi County, IDID8,4742+2%

40Owyhee County, IDID12,6612+12%

41Butte County, IDID2,7831−11%

42Camas County, IDID1,3161+9%

43Custer County, IDID4,6361−2%

44Clark County, IDID7830−23%

SHOWING 1–44 OF 44

Download CSV (full list, 44 rows)

UPDATED 2026-09-11 · DATA: US CENSUS BUREAU DECENNIAL CENSUS