Data / Rankings / Population aged 18 to 64 / Counties in Montana

Counties in Montana by population aged 18 to 64

Gallatin County had the highest population aged 18 to 64 of 56 counties in 2021, at 67.2%. Prairie County had the lowest, at 46.5%. The median was 53.8% and the figure for Montana was 58.4%. Source: the U.S. Census Bureau.

Keep it in a collection in your library.
Highest67.2Gallatin County
Lowest46.5Prairie County
Median53.856 counties
Montana58.4History

Map of counties, 2021

Beaverhead County: 56.5 %Big Horn County: 54.1 %Blaine County: 54.6 %Broadwater County: 56.3 %Carbon County: 55.2 %Carter County: 50.7 %Cascade County: 58.2 %Chouteau County: 54.4 %Custer County: 57.3 %Daniels County: 52.3 %Dawson County: 57.5 %Deer Lodge County: 58.3 %Fallon County: 55.3 %Fergus County: 52.7 %Flathead County: 56.4 %Gallatin County: 67.2 %Garfield County: 49.3 %Glacier County: 56.1 %Golden Valley County: 52.2 %Granite County: 53.8 %Hill County: 56.1 %Jefferson County: 54.9 %Judith Basin County: 51 %Lake County: 52.6 %Lewis and Clark County: 58.5 %Liberty County: 52.5 %Lincoln County: 50.6 %McCone County: 53.6 %Madison County: 53.5 %Meagher County: 54 %Mineral County: 53.2 %Missoula County: 63.1 %Musselshell County: 52.8 %Park County: 59.6 %Petroleum County: 53.8 %Phillips County: 52.3 %Pondera County: 53.7 %Powder River County: 52.1 %Powell County: 63.2 %Prairie County: 46.5 %Ravalli County: 52.9 %Richland County: 59.2 %Roosevelt County: 53.5 %Rosebud County: 54.1 %Sanders County: 50.3 %Sheridan County: 52.9 %Silver Bow County: 59.1 %Stillwater County: 53.8 %Sweet Grass County: 52.5 %Teton County: 52.5 %Toole County: 61.1 %Treasure County: 51 %Valley County: 54.1 %Wheatland County: 51.3 %Wibaux County: 53 %Yellowstone County: 58.9 %
  • Under 52
  • 52 to 53
  • 53 to 54
  • 54 to 55
  • 55 to 58
  • 58 and over
%, 2021. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2021

Gallatin County: 67.2 %Gallatin County67.2Powell County: 63.2 %Powell County63.2Missoula County: 63.1 %Missoula County63.1Toole County: 61.1 %Toole County61.1Park County: 59.6 %Park County59.6Richland County: 59.2 %Richland County59.2Silver Bow County: 59.1 %Silver Bow County59.1Yellowstone County: 58.9 %Yellowstone County58.9Lewis and Clark County: 58.5 %Lewis and Clark County58.5Deer Lodge County: 58.3 %Deer Lodge County58.3Cascade County: 58.2 %Cascade County58.2Dawson County: 57.5 %Dawson County57.5Custer County: 57.3 %Custer County57.3Beaverhead County: 56.5 %Beaverhead County56.5Flathead County: 56.4 %Flathead County56.4Broadwater County: 56.3 %Broadwater County56.3Hill County: 56.1 %Hill County56.1Glacier County: 56.1 %Glacier County56.1Fallon County: 55.3 %Fallon County55.3Carbon County: 55.2 %Carbon County55.2Jefferson County: 54.9 %Jefferson County54.9Blaine County: 54.6 %Blaine County54.6Chouteau County: 54.4 %Chouteau County54.4Rosebud County: 54.1 %Rosebud County54.1Big Horn County: 54.1 %Big Horn County54.1Valley County: 54.1 %Valley County54.1Meagher County: 54 %Meagher County54Petroleum County: 53.8 %Petroleum County53.8Stillwater County: 53.8 %Stillwater County53.8Granite County: 53.8 %Granite County53.8Pondera County: 53.7 %Pondera County53.7McCone County: 53.6 %McCone County53.6Roosevelt County: 53.5 %Roosevelt County53.5Madison County: 53.5 %Madison County53.5Mineral County: 53.2 %Mineral County53.2Wibaux County: 53 %Wibaux County53Ravalli County: 52.9 %Ravalli County52.9Sheridan County: 52.9 %Sheridan County52.9Musselshell County: 52.8 %Musselshell County52.8Fergus County: 52.7 %Fergus County52.7Lake County: 52.6 %Lake County52.6Sweet Grass County: 52.5 %Sweet Grass County52.5Liberty County: 52.5 %Liberty County52.5Teton County: 52.5 %Teton County52.5Daniels County: 52.3 %Daniels County52.3Phillips County: 52.3 %Phillips County52.3Golden Valley County: 52.2 %Golden Valley County52.2Powder River County: 52.1 %Powder River County52.1Wheatland County: 51.3 %Wheatland County51.3Treasure County: 51 %Treasure County51Judith Basin County: 51 %Judith Basin County51Carter County: 50.7 %Carter County50.7Lincoln County: 50.6 %Lincoln County50.6Sanders County: 50.3 %Sanders County50.3Garfield County: 49.3 %Garfield County49.3Prairie County: 46.5 %Prairie County46.5Gallatin County: 67.2 %Gallatin County67.2Powell County: 63.2 %Powell County63.2Missoula County: 63.1 %Missoula County63.1Toole County: 61.1 %Toole County61.1Park County: 59.6 %Park County59.6Richland County: 59.2 %Richland County59.2Silver Bow County: 59.1 %Silver Bow County59.1Yellowstone County: 58.9 %Yellowstone County58.9Lewis and Clark County: 58.5 %Lewis and Clark County58.5Deer Lodge County: 58.3 %Deer Lodge County58.3Cascade County: 58.2 %Cascade County58.2Dawson County: 57.5 %Dawson County57.5Custer County: 57.3 %Custer County57.3Beaverhead County: 56.5 %Beaverhead County56.5Flathead County: 56.4 %Flathead County56.4Broadwater County: 56.3 %Broadwater County56.3Hill County: 56.1 %Hill County56.1Glacier County: 56.1 %Glacier County56.1Fallon County: 55.3 %Fallon County55.3Carbon County: 55.2 %Carbon County55.2Jefferson County: 54.9 %Jefferson County54.9Blaine County: 54.6 %Blaine County54.6Chouteau County: 54.4 %Chouteau County54.4Rosebud County: 54.1 %Rosebud County54.1Big Horn County: 54.1 %Big Horn County54.1Valley County: 54.1 %Valley County54.1Meagher County: 54 %Meagher County54Petroleum County: 53.8 %Petroleum County53.8Stillwater County: 53.8 %Stillwater County53.8Granite County: 53.8 %Granite County53.8Pondera County: 53.7 %Pondera County53.7McCone County: 53.6 %McCone County53.6Roosevelt County: 53.5 %Roosevelt County53.5Madison County: 53.5 %Madison County53.5Mineral County: 53.2 %Mineral County53.2Wibaux County: 53 %Wibaux County53Ravalli County: 52.9 %Ravalli County52.9Sheridan County: 52.9 %Sheridan County52.9Musselshell County: 52.8 %Musselshell County52.8Fergus County: 52.7 %Fergus County52.7Lake County: 52.6 %Lake County52.6Sweet Grass County: 52.5 %Sweet Grass County52.5Liberty County: 52.5 %Liberty County52.5Teton County: 52.5 %Teton County52.5Daniels County: 52.3 %Daniels County52.3Phillips County: 52.3 %Phillips County52.3Golden Valley County: 52.2 %Golden Valley County52.2Powder River County: 52.1 %Powder River County52.1Wheatland County: 51.3 %Wheatland County51.3Treasure County: 51 %Treasure County51Judith Basin County: 51 %Judith Basin County51Carter County: 50.7 %Carter County50.7Lincoln County: 50.6 %Lincoln County50.6Sanders County: 50.3 %Sanders County50.3Garfield County: 49.3 %Garfield County49.3Prairie County: 46.5 %Prairie County46.5
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2021 (%)Change on 2020
1Gallatin County67.2+0.1 pts
2Powell County63.2-0.1 pts
3Missoula County63.1-0.1 pts
4Toole County61.1-0.2 pts
5Park County59.6-0.2 pts
6Richland County59.2-0.5 pts
7Silver Bow County59.1-0 pts
8Yellowstone County58.9-0.1 pts
9Lewis and Clark County58.5-0.2 pts
10Deer Lodge County58.3-0.1 pts
11Cascade County58.2-0.2 pts
12Dawson County57.5-0.2 pts
13Custer County57.3-0.1 pts
14Beaverhead County56.5+0.1 pts
15Flathead County56.4-0.2 pts
16Broadwater County56.30 pts
17Hill County56.1-0.2 pts
18Glacier County56.1+0.1 pts
19Fallon County55.3-0.3 pts
20Carbon County55.2-0.4 pts
21Jefferson County54.9-0.1 pts
22Blaine County54.6-0.3 pts
23Chouteau County54.4-0.2 pts
24Rosebud County54.1-0.6 pts
25Big Horn County54.1+0.9 pts
26Valley County54.1-0 pts
27Meagher County54+0.3 pts
28Petroleum County53.8+1.1 pts
29Stillwater County53.8-0.6 pts
30Granite County53.8+1.1 pts
31Pondera County53.70 pts
32McCone County53.6-1.3 pts
33Roosevelt County53.5-0.6 pts
34Madison County53.5+0.2 pts
35Mineral County53.20 pts
36Wibaux County53+0.6 pts
37Ravalli County52.9+0.2 pts
38Sheridan County52.9-1 pts
39Musselshell County52.8-0.2 pts
40Fergus County52.7-0.2 pts
41Lake County52.6-0 pts
42Sweet Grass County52.5-0.1 pts
43Liberty County52.5-0.2 pts
44Teton County52.5+0.1 pts
45Daniels County52.30 pts
46Phillips County52.3-1.2 pts
47Golden Valley County52.2-0.7 pts
48Powder River County52.1-1.4 pts
49Wheatland County51.3-0.6 pts
50Treasure County51+0.8 pts
51Judith Basin County51-0.8 pts
52Carter County50.7-0.3 pts
53Lincoln County50.6-0.3 pts
54Sanders County50.3+0.3 pts
55Garfield County49.3+0.9 pts
56Prairie County46.5-1.6 pts

Other periods

About this ranking

Residents aged 18 to 64 as a percentage of total population on 1 July. United States: Census Bureau county population estimates by age; states and the nation are sums of their counties.

Not comparable with working-age shares for ages 15 to 64 used in EU and World Bank statistics.

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: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. 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: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties (Counties in Montana by population aged 18 to 64, 2021) [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: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties, Counties in Montana by population aged 18 to 64, 2021. U.S. Census Bureau, 25 June 2026, https://www.census.gov/programs-surveys/popest/data/data-sets.html. Invokely, https://invokely.ai/rankings/population-18-64/montana-counties?period=2021. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Census Bureau. 2026. Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. Counties in Montana by population aged 18 to 64, 2021. Dataset. Accessed October 12, 2026. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Also distributed by Invokely, https://invokely.ai/rankings/population-18-64/montana-counties?period=2021.

Harvard

U.S. Census Bureau (2026) Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties, Counties in Montana by population aged 18 to 64, 2021 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/population-18-64/montana-counties?period=2021 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_montana_by_2021,
  author = {{U.S. Census Bureau}},
  title = {{Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties: Counties in Montana by population aged 18 to 64, 2021}},
  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/population-18-64/montana-counties?period=2021. Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. 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: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties: Counties in Montana by population aged 18 to 64, 2021
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/population-18-64/montana-counties?period=2021
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/montana-counties?period=2021.
N1  - Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.
ER  -
Embed this chart

Paste this code into a web page or a blog post. The chart shows the latest figures as they are published, with the source and a link back to this page.

Sites that read oEmbed links, such as WordPress, can show the chart when you paste the link to this page.

Use this data in your AI agent

Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:

Rank Counties in Montana by population aged 18 to 64 using official data, and cite the source.
rank_places {"indicator":"population_18_64_share","level":"province","within":"Montana","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=population_18_64_share&level=province&within=Montana&limit=10

Connect Claude, ChatGPT or Cursor in one step. The trial answers 25 calls a day without an account.

Questions

Which county has the highest population aged 18 to 64?

Gallatin County, with 67.2% in 2021, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Prairie County, with 46.5% in 2021.

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: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. Retrieved 2026-10-12.

Population aged 18 to 64: other rankings

Counties in Montana: more rankings