Data / Rankings / Median age / Counties in Idaho

Counties in Idaho by median age, 2024

Custer County had the highest median age of 44 counties in 2024, at 60 years. Madison County had the lowest, at 21.4 years. The median was 39.3 years and the figure for Idaho was 37.3 years. Source: the U.S. Census Bureau.

Highest60Custer County
Lowest21.4Madison County
Median39.344 counties
Idaho37.3History

All counties, 2024

CSVChart (SVG)

Custer CountyCuster County: 60 years60Adams CountyAdams County: 53.9 years53.9Boise CountyBoise County: 53.4 years53.4Lemhi CountyLemhi County: 53.3 years53.3Clearwater CountyClearwater County: 52.2 years52.2Idaho CountyIdaho County: 49.4 years49.4Lewis CountyLewis County: 49 years49Bonner CountyBonner County: 48.1 years48.1Valley CountyValley County: 46.9 years46.9Blaine CountyBlaine County: 45.6 years45.6Benewah CountyBenewah County: 45.5 years45.5Washington CountyWashington County: 45 years45Shoshone CountyShoshone County: 44.8 years44.8Gem CountyGem County: 44.2 years44.2Boundary CountyBoundary County: 43.7 years43.7Butte CountyButte County: 41.3 years41.3Nez Perce CountyNez Perce County: 41.2 years41.2Kootenai CountyKootenai County: 40.9 years40.9Oneida CountyOneida County: 40.8 years40.8Bear Lake CountyBear Lake County: 40.5 years40.5Fremont CountyFremont County: 40 years40Teton CountyTeton County: 39.6 years39.6Owyhee CountyOwyhee County: 39 years39Payette CountyPayette County: 38.9 years38.9Caribou CountyCaribou County: 38.5 years38.5Ada CountyAda County: 38.4 years38.4Gooding CountyGooding County: 38.1 years38.1Lincoln CountyLincoln County: 37.2 years37.2Camas CountyCamas County: 36.8 years36.8Twin Falls CountyTwin Falls County: 36.1 years36.1Bannock CountyBannock County: 35.2 years35.2Bingham CountyBingham County: 35 years35Canyon CountyCanyon County: 34.9 years34.9Minidoka CountyMinidoka County: 34.9 years34.9Power CountyPower County: 34.6 years34.6Jerome CountyJerome County: 34 years34Bonneville CountyBonneville County: 33.6 years33.6Franklin CountyFranklin County: 33.3 years33.3Cassia CountyCassia County: 33.2 years33.2Elmore CountyElmore County: 33.1 years33.1Jefferson CountyJefferson County: 32.8 years32.8Clark CountyClark County: 31.1 years31.1Latah CountyLatah County: 30.6 years30.6Madison CountyMadison County: 21.4 years21.4
years. Source: U.S. Census Bureau. Retrieved 2026-10-08.

Full ranking

RankCounties2024
years		Change on 2023
1Custer County60+0.5
2Adams County53.9-0.4
3Boise County53.4-0.1
4Lemhi County53.3+0.2
5Clearwater County52.2+0.2
6Idaho County49.4-0.2
7Lewis County49+0.1
8Bonner County48.1-0.1
9Valley County46.9-2.1
10Blaine County45.6+0.1
11Benewah County45.5-0.5
12Washington County45+0.4
13Shoshone County44.8-0.3
14Gem County44.2+1.4
15Boundary County43.7+0.9
16Butte County41.3+2.1
17Nez Perce County41.2+0.3
18Kootenai County40.9+0.1
19Oneida County40.8+0.6
20Bear Lake County40.5+0.3
21Fremont County40+0.1
22Teton County39.6-0.2
23Owyhee County39+0.7
24Payette County38.9+0.1
25Caribou County38.5+0.5
26Ada County38.4+0.1
27Gooding County38.1-0.3
28Lincoln County37.20
29Camas County36.8+1.9
30Twin Falls County36.1+0.3
31Bannock County35.2+0.2
32Bingham County35+0.2
33Canyon County34.9+0.1
33Minidoka County34.9+0.4
35Power County34.6+0.7
36Jerome County34+0.4
37Bonneville County33.6+0.3
38Franklin County33.3+0.8
39Cassia County33.2+0.1
40Elmore County33.1+0.6
41Jefferson County32.8+0.5
42Clark County31.1-2.3
43Latah County30.6-0.1
44Madison County21.40

Other periods

About this ranking

Age that divides the resident population into two halves of equal size. Spain and the EU: on 1 January. United States: American Community Survey five-year estimate, where the period shown is the last year of the five-year span.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. Equal values share a rank.

How to cite

U.S. Census Bureau. American Community Survey 5-year estimates, table B01002: median age, total population. https://www2.census.gov/programs-surveys/acs/summary_file/2024/table-based-SF/data/5YRData/acsdt5y2024-b01002.dat. Retrieved 2026-10-08.

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Questions

Which county has the highest median age?

Custer County, with 60 years in 2024, according to the U.S. Census Bureau.

Which county has the lowest median age?

Madison County, with 21.4 years in 2024.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Census Bureau, American Community Survey 5-year estimates, table B01002: median age, total population. Retrieved 2026-10-08.

Median age: other rankings

Counties in Idaho: more rankings