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 2019, at 67.1%. Garfield County had the lowest, at 48.9%. The median was 54.5% and the figure for Montana was 58.9%. Source: the U.S. Census Bureau.

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Highest67.1Gallatin County
Lowest48.9Garfield County
Median54.556 counties
Montana58.9History

Map of counties, 2019

Beaverhead County: 57.2 %Big Horn County: 53.4 %Blaine County: 55.1 %Broadwater County: 55.9 %Carbon County: 55.8 %Carter County: 51.5 %Cascade County: 58.9 %Chouteau County: 53.2 %Custer County: 57.4 %Daniels County: 53.1 %Dawson County: 57.9 %Deer Lodge County: 58.4 %Fallon County: 55.9 %Fergus County: 53.2 %Flathead County: 57.2 %Gallatin County: 67.1 %Garfield County: 48.9 %Glacier County: 56.2 %Golden Valley County: 51.1 %Granite County: 53.4 %Hill County: 57.8 %Jefferson County: 55.8 %Judith Basin County: 53.9 %Lake County: 53 %Lewis and Clark County: 59.3 %Liberty County: 53.2 %Lincoln County: 52.1 %McCone County: 54.4 %Madison County: 54.2 %Meagher County: 53.5 %Mineral County: 53.9 %Missoula County: 63.6 %Musselshell County: 53.8 %Park County: 60.3 %Petroleum County: 55.4 %Phillips County: 53.4 %Pondera County: 53.5 %Powder River County: 54.2 %Powell County: 63.5 %Prairie County: 50.8 %Ravalli County: 53.2 %Richland County: 60.4 %Roosevelt County: 55.7 %Rosebud County: 56 %Sanders County: 50.4 %Sheridan County: 55.3 %Silver Bow County: 59.8 %Stillwater County: 55.6 %Sweet Grass County: 52.5 %Teton County: 52.7 %Toole County: 62.9 %Treasure County: 51.5 %Valley County: 54.5 %Wheatland County: 53.7 %Wibaux County: 51.9 %Yellowstone County: 59.3 %
  • Under 53
  • 53 to 54
  • 54 to 56
  • 56 to 59
  • 59 and over
%, 2019. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2019

Gallatin County: 67.1 %Gallatin County67.1Missoula County: 63.6 %Missoula County63.6Powell County: 63.5 %Powell County63.5Toole County: 62.9 %Toole County62.9Richland County: 60.4 %Richland County60.4Park County: 60.3 %Park County60.3Silver Bow County: 59.8 %Silver Bow County59.8Lewis and Clark County: 59.3 %Lewis and Clark County59.3Yellowstone County: 59.3 %Yellowstone County59.3Cascade County: 58.9 %Cascade County58.9Deer Lodge County: 58.4 %Deer Lodge County58.4Dawson County: 57.9 %Dawson County57.9Hill County: 57.8 %Hill County57.8Custer County: 57.4 %Custer County57.4Beaverhead County: 57.2 %Beaverhead County57.2Flathead County: 57.2 %Flathead County57.2Glacier County: 56.2 %Glacier County56.2Rosebud County: 56 %Rosebud County56Broadwater County: 55.9 %Broadwater County55.9Fallon County: 55.9 %Fallon County55.9Jefferson County: 55.8 %Jefferson County55.8Carbon County: 55.8 %Carbon County55.8Roosevelt County: 55.7 %Roosevelt County55.7Stillwater County: 55.6 %Stillwater County55.6Petroleum County: 55.4 %Petroleum County55.4Sheridan County: 55.3 %Sheridan County55.3Blaine County: 55.1 %Blaine County55.1Valley County: 54.5 %Valley County54.5McCone County: 54.4 %McCone County54.4Madison County: 54.2 %Madison County54.2Powder River County: 54.2 %Powder River County54.2Judith Basin County: 53.9 %Judith Basin County53.9Mineral County: 53.9 %Mineral County53.9Musselshell County: 53.8 %Musselshell County53.8Wheatland County: 53.7 %Wheatland County53.7Meagher County: 53.5 %Meagher County53.5Pondera County: 53.5 %Pondera County53.5Granite County: 53.4 %Granite County53.4Big Horn County: 53.4 %Big Horn County53.4Phillips County: 53.4 %Phillips County53.4Chouteau County: 53.2 %Chouteau County53.2Fergus County: 53.2 %Fergus County53.2Ravalli County: 53.2 %Ravalli County53.2Liberty County: 53.2 %Liberty County53.2Daniels County: 53.1 %Daniels County53.1Lake County: 53 %Lake County53Teton County: 52.7 %Teton County52.7Sweet Grass County: 52.5 %Sweet Grass County52.5Lincoln County: 52.1 %Lincoln County52.1Wibaux County: 51.9 %Wibaux County51.9Carter County: 51.5 %Carter County51.5Treasure County: 51.5 %Treasure County51.5Golden Valley County: 51.1 %Golden Valley County51.1Prairie County: 50.8 %Prairie County50.8Sanders County: 50.4 %Sanders County50.4Garfield County: 48.9 %Garfield County48.9Gallatin County: 67.1 %Gallatin County67.1Missoula County: 63.6 %Missoula County63.6Powell County: 63.5 %Powell County63.5Toole County: 62.9 %Toole County62.9Richland County: 60.4 %Richland County60.4Park County: 60.3 %Park County60.3Silver Bow County: 59.8 %Silver Bow County59.8Lewis and Clark County: 59.3 %Lewis and Clark County59.3Yellowstone County: 59.3 %Yellowstone County59.3Cascade County: 58.9 %Cascade County58.9Deer Lodge County: 58.4 %Deer Lodge County58.4Dawson County: 57.9 %Dawson County57.9Hill County: 57.8 %Hill County57.8Custer County: 57.4 %Custer County57.4Beaverhead County: 57.2 %Beaverhead County57.2Flathead County: 57.2 %Flathead County57.2Glacier County: 56.2 %Glacier County56.2Rosebud County: 56 %Rosebud County56Broadwater County: 55.9 %Broadwater County55.9Fallon County: 55.9 %Fallon County55.9Jefferson County: 55.8 %Jefferson County55.8Carbon County: 55.8 %Carbon County55.8Roosevelt County: 55.7 %Roosevelt County55.7Stillwater County: 55.6 %Stillwater County55.6Petroleum County: 55.4 %Petroleum County55.4Sheridan County: 55.3 %Sheridan County55.3Blaine County: 55.1 %Blaine County55.1Valley County: 54.5 %Valley County54.5McCone County: 54.4 %McCone County54.4Madison County: 54.2 %Madison County54.2Powder River County: 54.2 %Powder River County54.2Judith Basin County: 53.9 %Judith Basin County53.9Mineral County: 53.9 %Mineral County53.9Musselshell County: 53.8 %Musselshell County53.8Wheatland County: 53.7 %Wheatland County53.7Meagher County: 53.5 %Meagher County53.5Pondera County: 53.5 %Pondera County53.5Granite County: 53.4 %Granite County53.4Big Horn County: 53.4 %Big Horn County53.4Phillips County: 53.4 %Phillips County53.4Chouteau County: 53.2 %Chouteau County53.2Fergus County: 53.2 %Fergus County53.2Ravalli County: 53.2 %Ravalli County53.2Liberty County: 53.2 %Liberty County53.2Daniels County: 53.1 %Daniels County53.1Lake County: 53 %Lake County53Teton County: 52.7 %Teton County52.7Sweet Grass County: 52.5 %Sweet Grass County52.5Lincoln County: 52.1 %Lincoln County52.1Wibaux County: 51.9 %Wibaux County51.9Carter County: 51.5 %Carter County51.5Treasure County: 51.5 %Treasure County51.5Golden Valley County: 51.1 %Golden Valley County51.1Prairie County: 50.8 %Prairie County50.8Sanders County: 50.4 %Sanders County50.4Garfield County: 48.9 %Garfield County48.9
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2019 (%)Change on 2018
1Gallatin County67.1-0.1 pts
2Missoula County63.6-0.5 pts
3Powell County63.5-0.8 pts
4Toole County62.9-0.3 pts
5Richland County60.4-0.1 pts
6Park County60.3-0.1 pts
7Silver Bow County59.8-0.3 pts
8Lewis and Clark County59.3-0.6 pts
9Yellowstone County59.3-0.2 pts
10Cascade County58.9-0.5 pts
11Deer Lodge County58.4-0.5 pts
12Dawson County57.9-0.4 pts
13Hill County57.8-0.1 pts
14Custer County57.4-0.2 pts
15Beaverhead County57.2-0.6 pts
16Flathead County57.2-0.6 pts
17Glacier County56.2-0.7 pts
18Rosebud County56-0.3 pts
19Broadwater County55.9-0 pts
20Fallon County55.9-0.9 pts
21Jefferson County55.8-0.8 pts
22Carbon County55.8-0.6 pts
23Roosevelt County55.7+0.1 pts
24Stillwater County55.6-0.3 pts
25Petroleum County55.4+2.1 pts
26Sheridan County55.3-0.8 pts
27Blaine County55.1-0.6 pts
28Valley County54.5-0.3 pts
29McCone County54.4-0.9 pts
30Madison County54.2-0.6 pts
31Powder River County54.2-0.3 pts
32Judith Basin County53.9-0.5 pts
33Mineral County53.9-0.6 pts
34Musselshell County53.8-1 pts
35Wheatland County53.7+0.4 pts
36Meagher County53.5+0.8 pts
37Pondera County53.5-0.9 pts
38Granite County53.4-0.1 pts
39Big Horn County53.4-0.3 pts
40Phillips County53.4-0.9 pts
41Chouteau County53.2-0.6 pts
42Fergus County53.2-0.8 pts
43Ravalli County53.2-0.6 pts
44Liberty County53.2-2.1 pts
45Daniels County53.10 pts
46Lake County53-0.6 pts
47Teton County52.7-0.4 pts
48Sweet Grass County52.5-1.1 pts
49Lincoln County52.1-0.8 pts
50Wibaux County51.9-1.5 pts
51Carter County51.5-1 pts
52Treasure County51.5-0.4 pts
53Golden Valley County51.1+0.2 pts
54Prairie County50.8-1.3 pts
55Sanders County50.4-0.8 pts
56Garfield County48.9-3 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, 2019) [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, 2019. 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=2019. 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, 2019. 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=2019.

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, 2019 [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=2019 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_montana_by_2019,
  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, 2019}},
  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=2019. 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, 2019
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=2019
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/montana-counties?period=2019.
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 2019, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Garfield County, with 48.9% in 2019.

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