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 2023, at 67.2%. Prairie County had the lowest, at 43.3%. The median was 53.3% and the figure for Montana was 57.9%. Source: the U.S. Census Bureau.

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Highest67.2Gallatin County
Lowest43.3Prairie County
Median53.356 counties
Montana57.9History

Map of counties, 2023

Beaverhead County: 56.8 %Big Horn County: 54.4 %Blaine County: 55.1 %Broadwater County: 55.9 %Carbon County: 53.5 %Carter County: 50.5 %Cascade County: 57.8 %Chouteau County: 53.5 %Custer County: 57.2 %Daniels County: 51 %Dawson County: 56.4 %Deer Lodge County: 57.5 %Fallon County: 53.5 %Fergus County: 51.7 %Flathead County: 56 %Gallatin County: 67.2 %Garfield County: 49.3 %Glacier County: 56.4 %Golden Valley County: 48.8 %Granite County: 54.3 %Hill County: 54.9 %Jefferson County: 53.8 %Judith Basin County: 51.9 %Lake County: 52.7 %Lewis and Clark County: 58 %Liberty County: 50.2 %Lincoln County: 50.4 %McCone County: 52.1 %Madison County: 53.8 %Meagher County: 53.1 %Mineral County: 53.1 %Missoula County: 62.8 %Musselshell County: 52.7 %Park County: 58.9 %Petroleum County: 50.4 %Phillips County: 52 %Pondera County: 52.7 %Powder River County: 50.6 %Powell County: 61.4 %Prairie County: 43.3 %Ravalli County: 52.1 %Richland County: 57.8 %Roosevelt County: 53.4 %Rosebud County: 53.2 %Sanders County: 49.9 %Sheridan County: 52.1 %Silver Bow County: 58.9 %Stillwater County: 52.5 %Sweet Grass County: 52.8 %Teton County: 51.9 %Toole County: 61.2 %Treasure County: 48.4 %Valley County: 53 %Wheatland County: 51 %Wibaux County: 53.5 %Yellowstone County: 58.3 %
  • Under 51
  • 51 to 52
  • 52 to 53
  • 53 to 55
  • 55 to 58
  • 58 and over
%, 2023. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2023

Gallatin County: 67.2 %Gallatin County67.2Missoula County: 62.8 %Missoula County62.8Powell County: 61.4 %Powell County61.4Toole County: 61.2 %Toole County61.2Silver Bow County: 58.9 %Silver Bow County58.9Park County: 58.9 %Park County58.9Yellowstone County: 58.3 %Yellowstone County58.3Lewis and Clark County: 58 %Lewis and Clark County58Richland County: 57.8 %Richland County57.8Cascade County: 57.8 %Cascade County57.8Deer Lodge County: 57.5 %Deer Lodge County57.5Custer County: 57.2 %Custer County57.2Beaverhead County: 56.8 %Beaverhead County56.8Dawson County: 56.4 %Dawson County56.4Glacier County: 56.4 %Glacier County56.4Flathead County: 56 %Flathead County56Broadwater County: 55.9 %Broadwater County55.9Blaine County: 55.1 %Blaine County55.1Hill County: 54.9 %Hill County54.9Big Horn County: 54.4 %Big Horn County54.4Granite County: 54.3 %Granite County54.3Jefferson County: 53.8 %Jefferson County53.8Madison County: 53.8 %Madison County53.8Carbon County: 53.5 %Carbon County53.5Fallon County: 53.5 %Fallon County53.5Chouteau County: 53.5 %Chouteau County53.5Wibaux County: 53.5 %Wibaux County53.5Roosevelt County: 53.4 %Roosevelt County53.4Rosebud County: 53.2 %Rosebud County53.2Meagher County: 53.1 %Meagher County53.1Mineral County: 53.1 %Mineral County53.1Valley County: 53 %Valley County53Sweet Grass County: 52.8 %Sweet Grass County52.8Pondera County: 52.7 %Pondera County52.7Musselshell County: 52.7 %Musselshell County52.7Lake County: 52.7 %Lake County52.7Stillwater County: 52.5 %Stillwater County52.5Ravalli County: 52.1 %Ravalli County52.1Sheridan County: 52.1 %Sheridan County52.1McCone County: 52.1 %McCone County52.1Phillips County: 52 %Phillips County52Teton County: 51.9 %Teton County51.9Judith Basin County: 51.9 %Judith Basin County51.9Fergus County: 51.7 %Fergus County51.7Wheatland County: 51 %Wheatland County51Daniels County: 51 %Daniels County51Powder River County: 50.6 %Powder River County50.6Carter County: 50.5 %Carter County50.5Lincoln County: 50.4 %Lincoln County50.4Petroleum County: 50.4 %Petroleum County50.4Liberty County: 50.2 %Liberty County50.2Sanders County: 49.9 %Sanders County49.9Garfield County: 49.3 %Garfield County49.3Golden Valley County: 48.8 %Golden Valley County48.8Treasure County: 48.4 %Treasure County48.4Prairie County: 43.3 %Prairie County43.3Gallatin County: 67.2 %Gallatin County67.2Missoula County: 62.8 %Missoula County62.8Powell County: 61.4 %Powell County61.4Toole County: 61.2 %Toole County61.2Silver Bow County: 58.9 %Silver Bow County58.9Park County: 58.9 %Park County58.9Yellowstone County: 58.3 %Yellowstone County58.3Lewis and Clark County: 58 %Lewis and Clark County58Richland County: 57.8 %Richland County57.8Cascade County: 57.8 %Cascade County57.8Deer Lodge County: 57.5 %Deer Lodge County57.5Custer County: 57.2 %Custer County57.2Beaverhead County: 56.8 %Beaverhead County56.8Dawson County: 56.4 %Dawson County56.4Glacier County: 56.4 %Glacier County56.4Flathead County: 56 %Flathead County56Broadwater County: 55.9 %Broadwater County55.9Blaine County: 55.1 %Blaine County55.1Hill County: 54.9 %Hill County54.9Big Horn County: 54.4 %Big Horn County54.4Granite County: 54.3 %Granite County54.3Jefferson County: 53.8 %Jefferson County53.8Madison County: 53.8 %Madison County53.8Carbon County: 53.5 %Carbon County53.5Fallon County: 53.5 %Fallon County53.5Chouteau County: 53.5 %Chouteau County53.5Wibaux County: 53.5 %Wibaux County53.5Roosevelt County: 53.4 %Roosevelt County53.4Rosebud County: 53.2 %Rosebud County53.2Meagher County: 53.1 %Meagher County53.1Mineral County: 53.1 %Mineral County53.1Valley County: 53 %Valley County53Sweet Grass County: 52.8 %Sweet Grass County52.8Pondera County: 52.7 %Pondera County52.7Musselshell County: 52.7 %Musselshell County52.7Lake County: 52.7 %Lake County52.7Stillwater County: 52.5 %Stillwater County52.5Ravalli County: 52.1 %Ravalli County52.1Sheridan County: 52.1 %Sheridan County52.1McCone County: 52.1 %McCone County52.1Phillips County: 52 %Phillips County52Teton County: 51.9 %Teton County51.9Judith Basin County: 51.9 %Judith Basin County51.9Fergus County: 51.7 %Fergus County51.7Wheatland County: 51 %Wheatland County51Daniels County: 51 %Daniels County51Powder River County: 50.6 %Powder River County50.6Carter County: 50.5 %Carter County50.5Lincoln County: 50.4 %Lincoln County50.4Petroleum County: 50.4 %Petroleum County50.4Liberty County: 50.2 %Liberty County50.2Sanders County: 49.9 %Sanders County49.9Garfield County: 49.3 %Garfield County49.3Golden Valley County: 48.8 %Golden Valley County48.8Treasure County: 48.4 %Treasure County48.4Prairie County: 43.3 %Prairie County43.3
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2023 (%)Change on 2022
1Gallatin County67.2+0.1 pts
2Missoula County62.8-0.2 pts
3Powell County61.4-0.5 pts
4Toole County61.2-0.1 pts
5Silver Bow County58.9-0.2 pts
6Park County58.9-0.5 pts
7Yellowstone County58.3-0.3 pts
8Lewis and Clark County58-0.3 pts
9Richland County57.8-1 pts
10Cascade County57.8-0.2 pts
11Deer Lodge County57.5-0.3 pts
12Custer County57.2-0.1 pts
13Beaverhead County56.80 pts
14Dawson County56.4-0.5 pts
15Glacier County56.4+0.1 pts
16Flathead County56-0.2 pts
17Broadwater County55.9-0 pts
18Blaine County55.1-0 pts
19Hill County54.9-0.5 pts
20Big Horn County54.4-0.1 pts
21Granite County54.3-0.3 pts
22Jefferson County53.8-0.5 pts
23Madison County53.8-0.3 pts
24Carbon County53.5-1 pts
25Fallon County53.5-0.5 pts
26Chouteau County53.5-0.3 pts
27Wibaux County53.5+0.1 pts
28Roosevelt County53.4-0.1 pts
29Rosebud County53.2-0.3 pts
30Meagher County53.1-0.7 pts
31Mineral County53.1-0.2 pts
32Valley County53-0.4 pts
33Sweet Grass County52.8+0.7 pts
34Pondera County52.70 pts
35Musselshell County52.7+0.3 pts
36Lake County52.7+0.1 pts
37Stillwater County52.5-0.5 pts
38Ravalli County52.1-0.5 pts
39Sheridan County52.1-0.1 pts
40McCone County52.1-1.1 pts
41Phillips County52+0.2 pts
42Teton County51.9-0.3 pts
43Judith Basin County51.9-0.3 pts
44Fergus County51.7-0.5 pts
45Wheatland County510 pts
46Daniels County51-0.2 pts
47Powder River County50.6-0.6 pts
48Carter County50.5+0.2 pts
49Lincoln County50.4-0.7 pts
50Petroleum County50.4-1.6 pts
51Liberty County50.2-1.1 pts
52Sanders County49.9-0.3 pts
53Garfield County49.3-0.3 pts
54Golden Valley County48.8-1.5 pts
55Treasure County48.4-2.2 pts
56Prairie County43.3-1.8 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, 2023) [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, 2023. 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=2023. 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, 2023. 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=2023.

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, 2023 [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=2023 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_montana_by_2023,
  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, 2023}},
  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=2023. 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, 2023
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=2023
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/montana-counties?period=2023.
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  -
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Questions

Which county has the highest population aged 18 to 64?

Gallatin County, with 67.2% in 2023, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Prairie County, with 43.3% in 2023.

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