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 2020, at 67.1%. Prairie County had the lowest, at 48.1%. The median was 54% and the figure for Montana was 58.5%. Source: the U.S. Census Bureau.

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Highest67.1Gallatin County
Lowest48.1Prairie County
Median5456 counties
Montana58.5History

Map of counties, 2020

Beaverhead County: 56.4 %Big Horn County: 53.3 %Blaine County: 54.9 %Broadwater County: 56.3 %Carbon County: 55.6 %Carter County: 50.9 %Cascade County: 58.4 %Chouteau County: 54.6 %Custer County: 57.4 %Daniels County: 52.3 %Dawson County: 57.7 %Deer Lodge County: 58.4 %Fallon County: 55.6 %Fergus County: 52.9 %Flathead County: 56.5 %Gallatin County: 67.1 %Garfield County: 48.4 %Glacier County: 56 %Golden Valley County: 52.9 %Granite County: 52.6 %Hill County: 56.4 %Jefferson County: 55 %Judith Basin County: 51.8 %Lake County: 52.6 %Lewis and Clark County: 58.7 %Liberty County: 52.7 %Lincoln County: 50.9 %McCone County: 54.9 %Madison County: 53.4 %Meagher County: 53.7 %Mineral County: 53.2 %Missoula County: 63.2 %Musselshell County: 53 %Park County: 59.8 %Petroleum County: 52.8 %Phillips County: 53.5 %Pondera County: 53.6 %Powder River County: 53.5 %Powell County: 63.3 %Prairie County: 48.1 %Ravalli County: 52.8 %Richland County: 59.7 %Roosevelt County: 54.1 %Rosebud County: 54.7 %Sanders County: 50 %Sheridan County: 53.9 %Silver Bow County: 59.1 %Stillwater County: 54.5 %Sweet Grass County: 52.6 %Teton County: 52.4 %Toole County: 61.3 %Treasure County: 50.3 %Valley County: 54.1 %Wheatland County: 51.9 %Wibaux County: 52.4 %Yellowstone County: 59 %
  • Under 52
  • 52 to 53
  • 53 to 54
  • 54 to 56
  • 56 to 58
  • 58 and over
%, 2020. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2020

Gallatin County: 67.1 %Gallatin County67.1Powell County: 63.3 %Powell County63.3Missoula County: 63.2 %Missoula County63.2Toole County: 61.3 %Toole County61.3Park County: 59.8 %Park County59.8Richland County: 59.7 %Richland County59.7Silver Bow County: 59.1 %Silver Bow County59.1Yellowstone County: 59 %Yellowstone County59Lewis and Clark County: 58.7 %Lewis and Clark County58.7Cascade County: 58.4 %Cascade County58.4Deer Lodge County: 58.4 %Deer Lodge County58.4Dawson County: 57.7 %Dawson County57.7Custer County: 57.4 %Custer County57.4Flathead County: 56.5 %Flathead County56.5Beaverhead County: 56.4 %Beaverhead County56.4Hill County: 56.4 %Hill County56.4Broadwater County: 56.3 %Broadwater County56.3Glacier County: 56 %Glacier County56Carbon County: 55.6 %Carbon County55.6Fallon County: 55.6 %Fallon County55.6Jefferson County: 55 %Jefferson County55Blaine County: 54.9 %Blaine County54.9McCone County: 54.9 %McCone County54.9Rosebud County: 54.7 %Rosebud County54.7Chouteau County: 54.6 %Chouteau County54.6Stillwater County: 54.5 %Stillwater County54.5Roosevelt County: 54.1 %Roosevelt County54.1Valley County: 54.1 %Valley County54.1Sheridan County: 53.9 %Sheridan County53.9Meagher County: 53.7 %Meagher County53.7Pondera County: 53.6 %Pondera County53.6Powder River County: 53.5 %Powder River County53.5Phillips County: 53.5 %Phillips County53.5Madison County: 53.4 %Madison County53.4Big Horn County: 53.3 %Big Horn County53.3Mineral County: 53.2 %Mineral County53.2Musselshell County: 53 %Musselshell County53Golden Valley County: 52.9 %Golden Valley County52.9Fergus County: 52.9 %Fergus County52.9Petroleum County: 52.8 %Petroleum County52.8Ravalli County: 52.8 %Ravalli County52.8Liberty County: 52.7 %Liberty County52.7Lake County: 52.6 %Lake County52.6Granite County: 52.6 %Granite County52.6Sweet Grass County: 52.6 %Sweet Grass County52.6Teton County: 52.4 %Teton County52.4Wibaux County: 52.4 %Wibaux County52.4Daniels County: 52.3 %Daniels County52.3Wheatland County: 51.9 %Wheatland County51.9Judith Basin County: 51.8 %Judith Basin County51.8Carter County: 50.9 %Carter County50.9Lincoln County: 50.9 %Lincoln County50.9Treasure County: 50.3 %Treasure County50.3Sanders County: 50 %Sanders County50Garfield County: 48.4 %Garfield County48.4Prairie County: 48.1 %Prairie County48.1Gallatin County: 67.1 %Gallatin County67.1Powell County: 63.3 %Powell County63.3Missoula County: 63.2 %Missoula County63.2Toole County: 61.3 %Toole County61.3Park County: 59.8 %Park County59.8Richland County: 59.7 %Richland County59.7Silver Bow County: 59.1 %Silver Bow County59.1Yellowstone County: 59 %Yellowstone County59Lewis and Clark County: 58.7 %Lewis and Clark County58.7Cascade County: 58.4 %Cascade County58.4Deer Lodge County: 58.4 %Deer Lodge County58.4Dawson County: 57.7 %Dawson County57.7Custer County: 57.4 %Custer County57.4Flathead County: 56.5 %Flathead County56.5Beaverhead County: 56.4 %Beaverhead County56.4Hill County: 56.4 %Hill County56.4Broadwater County: 56.3 %Broadwater County56.3Glacier County: 56 %Glacier County56Carbon County: 55.6 %Carbon County55.6Fallon County: 55.6 %Fallon County55.6Jefferson County: 55 %Jefferson County55Blaine County: 54.9 %Blaine County54.9McCone County: 54.9 %McCone County54.9Rosebud County: 54.7 %Rosebud County54.7Chouteau County: 54.6 %Chouteau County54.6Stillwater County: 54.5 %Stillwater County54.5Roosevelt County: 54.1 %Roosevelt County54.1Valley County: 54.1 %Valley County54.1Sheridan County: 53.9 %Sheridan County53.9Meagher County: 53.7 %Meagher County53.7Pondera County: 53.6 %Pondera County53.6Powder River County: 53.5 %Powder River County53.5Phillips County: 53.5 %Phillips County53.5Madison County: 53.4 %Madison County53.4Big Horn County: 53.3 %Big Horn County53.3Mineral County: 53.2 %Mineral County53.2Musselshell County: 53 %Musselshell County53Golden Valley County: 52.9 %Golden Valley County52.9Fergus County: 52.9 %Fergus County52.9Petroleum County: 52.8 %Petroleum County52.8Ravalli County: 52.8 %Ravalli County52.8Liberty County: 52.7 %Liberty County52.7Lake County: 52.6 %Lake County52.6Granite County: 52.6 %Granite County52.6Sweet Grass County: 52.6 %Sweet Grass County52.6Teton County: 52.4 %Teton County52.4Wibaux County: 52.4 %Wibaux County52.4Daniels County: 52.3 %Daniels County52.3Wheatland County: 51.9 %Wheatland County51.9Judith Basin County: 51.8 %Judith Basin County51.8Carter County: 50.9 %Carter County50.9Lincoln County: 50.9 %Lincoln County50.9Treasure County: 50.3 %Treasure County50.3Sanders County: 50 %Sanders County50Garfield County: 48.4 %Garfield County48.4Prairie County: 48.1 %Prairie County48.1
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2020 (%)Change on 2019
1Gallatin County67.1-0 pts
2Powell County63.3-0.2 pts
3Missoula County63.2-0.4 pts
4Toole County61.3-1.6 pts
5Park County59.8-0.5 pts
6Richland County59.7-0.7 pts
7Silver Bow County59.1-0.6 pts
8Yellowstone County59-0.3 pts
9Lewis and Clark County58.7-0.6 pts
10Cascade County58.4-0.5 pts
11Deer Lodge County58.4-0 pts
12Dawson County57.7-0.2 pts
13Custer County57.40 pts
14Flathead County56.5-0.7 pts
15Beaverhead County56.4-0.8 pts
16Hill County56.4-1.4 pts
17Broadwater County56.3+0.4 pts
18Glacier County56-0.2 pts
19Carbon County55.6-0.2 pts
20Fallon County55.6-0.3 pts
21Jefferson County55-0.8 pts
22Blaine County54.9-0.2 pts
23McCone County54.9+0.5 pts
24Rosebud County54.7-1.3 pts
25Chouteau County54.6+1.3 pts
26Stillwater County54.5-1.1 pts
27Roosevelt County54.1-1.5 pts
28Valley County54.1-0.4 pts
29Sheridan County53.9-1.4 pts
30Meagher County53.7+0.2 pts
31Pondera County53.6+0.2 pts
32Powder River County53.5-0.6 pts
33Phillips County53.5+0.1 pts
34Madison County53.4-0.8 pts
35Big Horn County53.3-0.2 pts
36Mineral County53.2-0.7 pts
37Musselshell County53-0.8 pts
38Golden Valley County52.9+1.8 pts
39Fergus County52.9-0.3 pts
40Petroleum County52.8-2.6 pts
41Ravalli County52.8-0.4 pts
42Liberty County52.7-0.4 pts
43Lake County52.6-0.4 pts
44Granite County52.6-0.8 pts
45Sweet Grass County52.6+0.1 pts
46Teton County52.4-0.4 pts
47Wibaux County52.4+0.5 pts
48Daniels County52.3-0.8 pts
49Wheatland County51.9-1.8 pts
50Judith Basin County51.8-2.2 pts
51Carter County50.9-0.6 pts
52Lincoln County50.9-1.2 pts
53Treasure County50.3-1.2 pts
54Sanders County50-0.4 pts
55Garfield County48.4-0.6 pts
56Prairie County48.1-2.8 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, 2020) [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, 2020. 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=2020. 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, 2020. 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=2020.

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, 2020 [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=2020 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_montana_by_2020,
  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, 2020}},
  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=2020. 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, 2020
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=2020
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/montana-counties?period=2020.
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 67.1% in 2020, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Prairie County, with 48.1% in 2020.

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