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

Counties in Montana by population aged 18 to 64, 2025

Gallatin County had the highest population aged 18 to 64 of 56 counties in 2025, at 67.4%. Prairie County had the lowest, at 41.2%. The median was 53.1% and the figure for Montana was 57.6%. Source: the U.S. Census Bureau.

Keep it in a collection in your library.
Highest67.4Gallatin County
Lowest41.2Prairie County
Median53.156 counties
Montana57.6History

Map of counties, 2025

Beaverhead County: 57.7 %Big Horn County: 54.5 %Blaine County: 54.3 %Broadwater County: 55.4 %Carbon County: 51.4 %Carter County: 49.7 %Cascade County: 57.6 %Chouteau County: 53.4 %Custer County: 56.4 %Daniels County: 50 %Dawson County: 55.6 %Deer Lodge County: 55.5 %Fallon County: 52.3 %Fergus County: 50.6 %Flathead County: 55.7 %Gallatin County: 67.4 %Garfield County: 49.1 %Glacier County: 56 %Golden Valley County: 47.9 %Granite County: 54.3 %Hill County: 54.3 %Jefferson County: 53.4 %Judith Basin County: 49.1 %Lake County: 52 %Lewis and Clark County: 57.6 %Liberty County: 51 %Lincoln County: 49.9 %McCone County: 51 %Madison County: 53.7 %Meagher County: 50.5 %Mineral County: 53.3 %Missoula County: 62.8 %Musselshell County: 52.1 %Park County: 58 %Petroleum County: 48.5 %Phillips County: 51.2 %Pondera County: 52.2 %Powder River County: 49.1 %Powell County: 59.4 %Prairie County: 41.2 %Ravalli County: 51.5 %Richland County: 57 %Roosevelt County: 53.2 %Rosebud County: 53.4 %Sanders County: 48.7 %Sheridan County: 53.5 %Silver Bow County: 58.4 %Stillwater County: 51.1 %Sweet Grass County: 51.8 %Teton County: 50.6 %Toole County: 60.5 %Treasure County: 46.4 %Valley County: 52.3 %Wheatland County: 50.4 %Wibaux County: 52.9 %Yellowstone County: 58.1 %
  • Under 50
  • 50 to 51
  • 51 to 53
  • 53 to 54
  • 54 to 57
  • 57 and over
%, 2025. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2025

Gallatin County: 67.4 %Gallatin County67.4Missoula County: 62.8 %Missoula County62.8Toole County: 60.5 %Toole County60.5Powell County: 59.4 %Powell County59.4Silver Bow County: 58.4 %Silver Bow County58.4Yellowstone County: 58.1 %Yellowstone County58.1Park County: 58 %Park County58Beaverhead County: 57.7 %Beaverhead County57.7Cascade County: 57.6 %Cascade County57.6Lewis and Clark County: 57.6 %Lewis and Clark County57.6Richland County: 57 %Richland County57Custer County: 56.4 %Custer County56.4Glacier County: 56 %Glacier County56Flathead County: 55.7 %Flathead County55.7Dawson County: 55.6 %Dawson County55.6Deer Lodge County: 55.5 %Deer Lodge County55.5Broadwater County: 55.4 %Broadwater County55.4Big Horn County: 54.5 %Big Horn County54.5Granite County: 54.3 %Granite County54.3Blaine County: 54.3 %Blaine County54.3Hill County: 54.3 %Hill County54.3Madison County: 53.7 %Madison County53.7Sheridan County: 53.5 %Sheridan County53.5Chouteau County: 53.4 %Chouteau County53.4Jefferson County: 53.4 %Jefferson County53.4Rosebud County: 53.4 %Rosebud County53.4Mineral County: 53.3 %Mineral County53.3Roosevelt County: 53.2 %Roosevelt County53.2Wibaux County: 52.9 %Wibaux County52.9Valley County: 52.3 %Valley County52.3Fallon County: 52.3 %Fallon County52.3Pondera County: 52.2 %Pondera County52.2Musselshell County: 52.1 %Musselshell County52.1Lake County: 52 %Lake County52Sweet Grass County: 51.8 %Sweet Grass County51.8Ravalli County: 51.5 %Ravalli County51.5Carbon County: 51.4 %Carbon County51.4Phillips County: 51.2 %Phillips County51.2Stillwater County: 51.1 %Stillwater County51.1Liberty County: 51 %Liberty County51McCone County: 51 %McCone County51Teton County: 50.6 %Teton County50.6Fergus County: 50.6 %Fergus County50.6Meagher County: 50.5 %Meagher County50.5Wheatland County: 50.4 %Wheatland County50.4Daniels County: 50 %Daniels County50Lincoln County: 49.9 %Lincoln County49.9Carter County: 49.7 %Carter County49.7Garfield County: 49.1 %Garfield County49.1Judith Basin County: 49.1 %Judith Basin County49.1Powder River County: 49.1 %Powder River County49.1Sanders County: 48.7 %Sanders County48.7Petroleum County: 48.5 %Petroleum County48.5Golden Valley County: 47.9 %Golden Valley County47.9Treasure County: 46.4 %Treasure County46.4Prairie County: 41.2 %Prairie County41.2Gallatin County: 67.4 %Gallatin County67.4Missoula County: 62.8 %Missoula County62.8Toole County: 60.5 %Toole County60.5Powell County: 59.4 %Powell County59.4Silver Bow County: 58.4 %Silver Bow County58.4Yellowstone County: 58.1 %Yellowstone County58.1Park County: 58 %Park County58Beaverhead County: 57.7 %Beaverhead County57.7Cascade County: 57.6 %Cascade County57.6Lewis and Clark County: 57.6 %Lewis and Clark County57.6Richland County: 57 %Richland County57Custer County: 56.4 %Custer County56.4Glacier County: 56 %Glacier County56Flathead County: 55.7 %Flathead County55.7Dawson County: 55.6 %Dawson County55.6Deer Lodge County: 55.5 %Deer Lodge County55.5Broadwater County: 55.4 %Broadwater County55.4Big Horn County: 54.5 %Big Horn County54.5Granite County: 54.3 %Granite County54.3Blaine County: 54.3 %Blaine County54.3Hill County: 54.3 %Hill County54.3Madison County: 53.7 %Madison County53.7Sheridan County: 53.5 %Sheridan County53.5Chouteau County: 53.4 %Chouteau County53.4Jefferson County: 53.4 %Jefferson County53.4Rosebud County: 53.4 %Rosebud County53.4Mineral County: 53.3 %Mineral County53.3Roosevelt County: 53.2 %Roosevelt County53.2Wibaux County: 52.9 %Wibaux County52.9Valley County: 52.3 %Valley County52.3Fallon County: 52.3 %Fallon County52.3Pondera County: 52.2 %Pondera County52.2Musselshell County: 52.1 %Musselshell County52.1Lake County: 52 %Lake County52Sweet Grass County: 51.8 %Sweet Grass County51.8Ravalli County: 51.5 %Ravalli County51.5Carbon County: 51.4 %Carbon County51.4Phillips County: 51.2 %Phillips County51.2Stillwater County: 51.1 %Stillwater County51.1Liberty County: 51 %Liberty County51McCone County: 51 %McCone County51Teton County: 50.6 %Teton County50.6Fergus County: 50.6 %Fergus County50.6Meagher County: 50.5 %Meagher County50.5Wheatland County: 50.4 %Wheatland County50.4Daniels County: 50 %Daniels County50Lincoln County: 49.9 %Lincoln County49.9Carter County: 49.7 %Carter County49.7Garfield County: 49.1 %Garfield County49.1Judith Basin County: 49.1 %Judith Basin County49.1Powder River County: 49.1 %Powder River County49.1Sanders County: 48.7 %Sanders County48.7Petroleum County: 48.5 %Petroleum County48.5Golden Valley County: 47.9 %Golden Valley County47.9Treasure County: 46.4 %Treasure County46.4Prairie County: 41.2 %Prairie County41.2
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2025 (%)Change on 2024
1Gallatin County67.4+0.1 pts
2Missoula County62.80 pts
3Toole County60.5-0.4 pts
4Powell County59.4-0.9 pts
5Silver Bow County58.4-0.3 pts
6Yellowstone County58.1-0.1 pts
7Park County58-0.7 pts
8Beaverhead County57.7+0.6 pts
9Cascade County57.6-0.2 pts
10Lewis and Clark County57.6-0.1 pts
11Richland County57-0.1 pts
12Custer County56.4-0.4 pts
13Glacier County56-0.3 pts
14Flathead County55.7-0.1 pts
15Dawson County55.6-0.5 pts
16Deer Lodge County55.5-1.1 pts
17Broadwater County55.40 pts
18Big Horn County54.50 pts
19Granite County54.3-0.6 pts
20Blaine County54.3-0.4 pts
21Hill County54.3-0.5 pts
22Madison County53.7-0.4 pts
23Sheridan County53.5+0.8 pts
24Chouteau County53.4+0.1 pts
25Jefferson County53.4-0.2 pts
26Rosebud County53.4-0.1 pts
27Mineral County53.3-0.1 pts
28Roosevelt County53.2-0.1 pts
29Wibaux County52.9-0.6 pts
30Valley County52.3-0.4 pts
31Fallon County52.3-0.5 pts
32Pondera County52.2-0.3 pts
33Musselshell County52.1-0.1 pts
34Lake County52-0.4 pts
35Sweet Grass County51.8-0.5 pts
36Ravalli County51.5-0.3 pts
37Carbon County51.4-1.1 pts
38Phillips County51.2-0.3 pts
39Stillwater County51.1-0.7 pts
40Liberty County51+0.9 pts
41McCone County51-0.1 pts
42Teton County50.6-0.8 pts
43Fergus County50.6-0.9 pts
44Meagher County50.5-1 pts
45Wheatland County50.4+0.3 pts
46Daniels County50-0.5 pts
47Lincoln County49.9-0.5 pts
48Carter County49.7-0.2 pts
49Garfield County49.1+0.2 pts
50Judith Basin County49.1-1.2 pts
51Powder River County49.1+0.3 pts
52Sanders County48.7-0.4 pts
53Petroleum County48.5-0.3 pts
54Golden Valley County47.9-0.1 pts
55Treasure County46.4+0.4 pts
56Prairie County41.2-0.6 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, 2025) [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, 2025. 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. 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, 2025. 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.

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, 2025 [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 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_montana_by_2025,
  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, 2025}},
  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. 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, 2025
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
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/montana-counties.
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 67.4% in 2025, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Prairie County, with 41.2% in 2025.

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