RANKING · 2024 ACS · 44 SHOWN OF 44

Oldest by median age, Idaho counties

Idaho counties ranked by median age of residents (2024 ACS). This list covers the 44 counties in Idaho that qualify, ranked against each other statewide. The median across all 44 is 39.6. Biggest climber in the top 100 since 2020: Blaine County, ID, up 5 places to #10.

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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

01▲1Custer County, IDID4,63660.0+46%

02▼1Adams County, IDID5,01353.9+21%

03Boise County, IDID8,54553.4+32%

04Lemhi County, IDID8,47453.3+25%

05Clearwater County, IDID9,11852.2+25%

06Idaho County, IDID17,87449.4+17%

07▲2Lewis County, IDID3,70449.0+15%

08Bonner County, IDID54,42048.1+18%

09▼2Valley County, IDID12,83146.9+8%

10▲5Blaine County, IDID25,51745.6+22%

11Benewah County, IDID10,50845.5+16%

12▲2Washington County, IDID11,58345.0+15%

13▼3Shoshone County, IDID14,13044.8+7%

14▲2Gem County, IDID21,77344.2+18%

15▼2Boundary County, IDID13,99743.7+14%

16▲1Butte County, IDID2,78341.3+6%

17▲2Nez Perce County, IDID42,90541.2+8%

18Kootenai County, IDID191,86440.9+13%

19▲1Oneida County, IDID5,08540.8+13%

20▲1Bear Lake County, IDID6,72740.5+13%

21▲4Fremont County, IDID14,20840.0+25%

22▲4Teton County, IDID13,25439.6+27%

23Owyhee County, IDID12,66139.0+19%

24▼2Payette County, IDID27,82438.9+13%

25▲2Caribou County, IDID7,25238.5+10%

26▲2Ada County, IDID546,14138.4+17%

27▲2Gooding County, IDID16,44638.1+9%

28▲2Lincoln County, IDID5,60337.2+8%

29▼17Camas County, IDID1,31636.8−7%

30▲1Twin Falls County, IDID97,53936.1+3%

31▲4Bannock County, IDID91,59135.2+18%

32▲2Bingham County, IDID51,15335.0+18%

33▲3Canyon County, IDID275,12334.9+14%

34▼1Minidoka County, IDID22,91134.9+4%

35▼3Power County, IDID8,24634.6+9%

36▲2Jerome County, IDID26,36234.0+3%

37▲2Bonneville County, IDID135,77133.6+6%

38▼1Franklin County, IDID15,88933.3+20%

39▲1Cassia County, IDID26,39733.2+7%

40▲1Elmore County, IDID29,46533.1+14%

41▲1Jefferson County, IDID35,29732.8+14%

42▼18Clark County, IDID78331.1+1%

43Latah County, IDID41,84230.6+10%

44Madison County, IDID55,17221.4+3%

SHOWING 1–44 OF 44

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UPDATED 2026-09-11 · DATA: US CENSUS BUREAU ACS 5-YEAR ESTIMATES