Counties in Montana by median age on 1 July (US county estimates)

Sanders County had the highest median age on 1 July (US county estimates) of 56 counties in 2017, at 54.3 years. Big Horn County had the lowest, at 30.1 years. The median was 45.7 years. Source: the U.S. Census Bureau.

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Highest54.3Sanders County
Lowest30.1Big Horn County
Median45.756 counties

Map of counties, 2017

Beaverhead County: 43 yearsBig Horn County: 30.1 yearsBlaine County: 34.5 yearsBroadwater County: 46.9 yearsCarbon County: 49.7 yearsCarter County: 47.1 yearsCascade County: 38.3 yearsChouteau County: 40 yearsCuster County: 40.6 yearsDaniels County: 47.3 yearsDawson County: 40.8 yearsDeer Lodge County: 48.4 yearsFallon County: 37.9 yearsFergus County: 46.8 yearsFlathead County: 42.5 yearsGallatin County: 33.1 yearsGarfield County: 42.6 yearsGlacier County: 32.5 yearsGolden Valley County: 52.1 yearsGranite County: 52.8 yearsHill County: 34.7 yearsJefferson County: 48.7 yearsJudith Basin County: 52.1 yearsLake County: 43.4 yearsLewis and Clark County: 41.2 yearsLiberty County: 42.8 yearsLincoln County: 53.2 yearsMcCone County: 47.7 yearsMadison County: 52.9 yearsMeagher County: 53.5 yearsMineral County: 53 yearsMissoula County: 36.5 yearsMusselshell County: 51.1 yearsPark County: 46.6 yearsPetroleum County: 50.9 yearsPhillips County: 44.9 yearsPondera County: 41.4 yearsPowder River County: 49.2 yearsPowell County: 46.4 yearsPrairie County: 52.6 yearsRavalli County: 49.2 yearsRichland County: 38 yearsRoosevelt County: 31.9 yearsRosebud County: 37.4 yearsSanders County: 54.3 yearsSheridan County: 45 yearsSilver Bow County: 41.6 yearsStillwater County: 48.1 yearsSweet Grass County: 47.4 yearsTeton County: 44.9 yearsToole County: 41.2 yearsTreasure County: 51.1 yearsValley County: 44.9 yearsWheatland County: 46.4 yearsWibaux County: 47.7 yearsYellowstone County: 38.3 years
  • Under 38
  • 38 to 42
  • 42 to 46
  • 46 to 48
  • 48 to 51
  • 51 and over
years, 2017. Source: U.S. Census Bureau, Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2017

Sanders County: 54.3 yearsSanders County54.3Meagher County: 53.5 yearsMeagher County53.5Lincoln County: 53.2 yearsLincoln County53.2Mineral County: 53 yearsMineral County53Madison County: 52.9 yearsMadison County52.9Granite County: 52.8 yearsGranite County52.8Prairie County: 52.6 yearsPrairie County52.6Golden Valley County: 52.1 yearsGolden Valley County52.1Judith Basin County: 52.1 yearsJudith Basin County52.1Musselshell County: 51.1 yearsMusselshell County51.1Treasure County: 51.1 yearsTreasure County51.1Petroleum County: 50.9 yearsPetroleum County50.9Carbon County: 49.7 yearsCarbon County49.7Powder River County: 49.2 yearsPowder River County49.2Ravalli County: 49.2 yearsRavalli County49.2Jefferson County: 48.7 yearsJefferson County48.7Deer Lodge County: 48.4 yearsDeer Lodge County48.4Stillwater County: 48.1 yearsStillwater County48.1McCone County: 47.7 yearsMcCone County47.7Wibaux County: 47.7 yearsWibaux County47.7Sweet Grass County: 47.4 yearsSweet Grass County47.4Daniels County: 47.3 yearsDaniels County47.3Carter County: 47.1 yearsCarter County47.1Broadwater County: 46.9 yearsBroadwater County46.9Fergus County: 46.8 yearsFergus County46.8Park County: 46.6 yearsPark County46.6Powell County: 46.4 yearsPowell County46.4Wheatland County: 46.4 yearsWheatland County46.4Sheridan County: 45 yearsSheridan County45Phillips County: 44.9 yearsPhillips County44.9Teton County: 44.9 yearsTeton County44.9Valley County: 44.9 yearsValley County44.9Lake County: 43.4 yearsLake County43.4Beaverhead County: 43 yearsBeaverhead County43Liberty County: 42.8 yearsLiberty County42.8Garfield County: 42.6 yearsGarfield County42.6Flathead County: 42.5 yearsFlathead County42.5Silver Bow County: 41.6 yearsSilver Bow County41.6Pondera County: 41.4 yearsPondera County41.4Lewis and Clark County: 41.2 yearsLewis and Clark County41.2Toole County: 41.2 yearsToole County41.2Dawson County: 40.8 yearsDawson County40.8Custer County: 40.6 yearsCuster County40.6Chouteau County: 40 yearsChouteau County40Cascade County: 38.3 yearsCascade County38.3Yellowstone County: 38.3 yearsYellowstone County38.3Richland County: 38 yearsRichland County38Fallon County: 37.9 yearsFallon County37.9Rosebud County: 37.4 yearsRosebud County37.4Missoula County: 36.5 yearsMissoula County36.5Hill County: 34.7 yearsHill County34.7Blaine County: 34.5 yearsBlaine County34.5Gallatin County: 33.1 yearsGallatin County33.1Glacier County: 32.5 yearsGlacier County32.5Roosevelt County: 31.9 yearsRoosevelt County31.9Big Horn County: 30.1 yearsBig Horn County30.1Sanders County: 54.3 yearsSanders County54.3Meagher County: 53.5 yearsMeagher County53.5Lincoln County: 53.2 yearsLincoln County53.2Mineral County: 53 yearsMineral County53Madison County: 52.9 yearsMadison County52.9Granite County: 52.8 yearsGranite County52.8Prairie County: 52.6 yearsPrairie County52.6Golden Valley County: 52.1 yearsGolden Valley County52.1Judith Basin County: 52.1 yearsJudith Basin County52.1Musselshell County: 51.1 yearsMusselshell County51.1Treasure County: 51.1 yearsTreasure County51.1Petroleum County: 50.9 yearsPetroleum County50.9Carbon County: 49.7 yearsCarbon County49.7Powder River County: 49.2 yearsPowder River County49.2Ravalli County: 49.2 yearsRavalli County49.2Jefferson County: 48.7 yearsJefferson County48.7Deer Lodge County: 48.4 yearsDeer Lodge County48.4Stillwater County: 48.1 yearsStillwater County48.1McCone County: 47.7 yearsMcCone County47.7Wibaux County: 47.7 yearsWibaux County47.7Sweet Grass County: 47.4 yearsSweet Grass County47.4Daniels County: 47.3 yearsDaniels County47.3Carter County: 47.1 yearsCarter County47.1Broadwater County: 46.9 yearsBroadwater County46.9Fergus County: 46.8 yearsFergus County46.8Park County: 46.6 yearsPark County46.6Powell County: 46.4 yearsPowell County46.4Wheatland County: 46.4 yearsWheatland County46.4Sheridan County: 45 yearsSheridan County45Phillips County: 44.9 yearsPhillips County44.9Teton County: 44.9 yearsTeton County44.9Valley County: 44.9 yearsValley County44.9Lake County: 43.4 yearsLake County43.4Beaverhead County: 43 yearsBeaverhead County43Liberty County: 42.8 yearsLiberty County42.8Garfield County: 42.6 yearsGarfield County42.6Flathead County: 42.5 yearsFlathead County42.5Silver Bow County: 41.6 yearsSilver Bow County41.6Pondera County: 41.4 yearsPondera County41.4Lewis and Clark County: 41.2 yearsLewis and Clark County41.2Toole County: 41.2 yearsToole County41.2Dawson County: 40.8 yearsDawson County40.8Custer County: 40.6 yearsCuster County40.6Chouteau County: 40 yearsChouteau County40Cascade County: 38.3 yearsCascade County38.3Yellowstone County: 38.3 yearsYellowstone County38.3Richland County: 38 yearsRichland County38Fallon County: 37.9 yearsFallon County37.9Rosebud County: 37.4 yearsRosebud County37.4Missoula County: 36.5 yearsMissoula County36.5Hill County: 34.7 yearsHill County34.7Blaine County: 34.5 yearsBlaine County34.5Gallatin County: 33.1 yearsGallatin County33.1Glacier County: 32.5 yearsGlacier County32.5Roosevelt County: 31.9 yearsRoosevelt County31.9Big Horn County: 30.1 yearsBig Horn County30.1
years. Source: U.S. Census Bureau, Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. Retrieved 2026-10-12.

Full ranking

Other periods

About this ranking

Age that divides the resident population of a US county into two halves of equal size on 1 July, from Census Bureau population estimates calculated by single year of age.

Counties only: the county file has no state or national medians, and medians cannot be added up. A single-year estimate, unlike median_age, which for US places is a five-year American Community Survey estimate.

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. Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.

Citation styles

The publisher is the author. Invokely is named only as the place the figures were read, where a style asks for it.

APA 7

U.S. Census Bureau. (2026). Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage (Counties in Montana by median age on 1 July (US county estimates), 2017) [Data set]. Retrieved October 12, 2026, from https://www.census.gov/programs-surveys/popest/data/data-sets.html

MLA 9

Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage, Counties in Montana by median age on 1 July (US county estimates), 2017. U.S. Census Bureau, 25 June 2026, https://www.census.gov/programs-surveys/popest/data/data-sets.html. Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/montana-counties?period=2017. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Census Bureau. 2026. Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. Counties in Montana by median age on 1 July (US county estimates), 2017. Dataset. Accessed October 12, 2026. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Also distributed by Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/montana-counties?period=2017.

Harvard

U.S. Census Bureau (2026) Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage, Counties in Montana by median age on 1 July (US county estimates), 2017 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/median-age-july-1-us-counties/montana-counties?period=2017 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_montana_by_2017,
  author = {{U.S. Census Bureau}},
  title = {{Population Estimates Program, county population by age and sex: median age (MEDIAN\_AGE\_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage: Counties in Montana by median age on 1 July (US county estimates), 2017}},
  year = {2026},
  howpublished = {Data set},
  url = {https://www.census.gov/programs-surveys/popest/data/data-sets.html},
  urldate = {2026-10-12},
  note = {Accessed via Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/montana-counties?period=2017. Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: median age (MEDIAN\_AGE\_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.},
}
RIS
TY  - DATA
AU  - U.S. Census Bureau
TI  - Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage: Counties in Montana by median age on 1 July (US county estimates), 2017
PY  - 2026
DA  - 2026/06/25
PB  - U.S. Census Bureau
DB  - Invokely
UR  - https://www.census.gov/programs-surveys/popest/data/data-sets.html
L2  - https://invokely.ai/rankings/median-age-july-1-us-counties/montana-counties?period=2017
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/montana-counties?period=2017.
N1  - Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.
ER  - 
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Questions

Which county has the highest median age on 1 July (US county estimates)?

Sanders County, with 54.3 years in 2017, according to the U.S. Census Bureau.

Which county has the lowest median age on 1 July (US county estimates)?

Big Horn County, with 30.1 years in 2017.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Census Bureau, Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. Retrieved 2026-10-12.

Median age on 1 July (US county estimates): other rankings

Counties in Montana: more rankings