RANKING · 2020 CENSUS · 44 SHOWN OF 44

Oldest by median age, Idaho counties · 2020

Idaho counties ranked by median age of residents (2020 ACS). 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

RELATEDLargest foreign-born population Most residents with a disability Largest veteran population Most uninsured people Largest senior population Most unmarried people

YEAR1990 2000 2010 2020 2024

RANKPLACESTATEPOPMEDIAN AGEVS 2000

01Adams County, IDID5,01354.9+24%

02Custer County, IDID4,63654.0+31%

03Boise County, IDID8,54553.9+33%

04Lemhi County, IDID8,47452.6+23%

05Clearwater County, IDID9,11852.1+25%

06Idaho County, IDID17,87451.4+22%

07Valley County, IDID12,83149.5+14%

08Bonner County, IDID54,42049.3+21%

09Lewis County, IDID3,70448.8+15%

10Shoshone County, IDID14,13048.2+15%

11Benewah County, IDID10,50847.5+21%

12Camas County, IDID1,31647.0+18%

13Boundary County, IDID13,99746.9+22%

14Washington County, IDID11,58346.0+17%

15Blaine County, IDID25,51745.4+21%

16Gem County, IDID21,77344.1+18%

17Butte County, IDID2,78342.7+10%

18Kootenai County, IDID191,86441.2+14%

19Nez Perce County, IDID42,90540.9+7%

20Oneida County, IDID5,08540.3+12%

21Bear Lake County, IDID6,72740.1+12%

22Payette County, IDID27,82439.4+15%

23Owyhee County, IDID12,66138.8+18%

24Clark County, IDID78337.9+23%

25Fremont County, IDID14,20837.7+18%

26Teton County, IDID13,25437.7+20%

27Caribou County, IDID7,25237.5+7%

28Ada County, IDID546,14137.4+14%

29Gooding County, IDID16,44637.1+6%

30Lincoln County, IDID5,60336.5+6%

31Twin Falls County, IDID97,53935.8+3%

32Power County, IDID8,24635.3+12%

33Minidoka County, IDID22,91135.2+5%

34Bingham County, IDID51,15334.8+17%

35Bannock County, IDID91,59134.7+16%

36Canyon County, IDID275,12334.5+13%

37Franklin County, IDID15,88933.9+22%

38Jerome County, IDID26,36233.4+2%

39Bonneville County, IDID135,77133.1+4%

40Cassia County, IDID26,39733.1+6%

41Elmore County, IDID29,46532.7+12%

42Jefferson County, IDID35,29732.1+11%

43Latah County, IDID41,84231.0+11%

44Madison County, IDID55,17223.1+12%

SHOWING 1–44 OF 44

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