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 2015, at 68%. Petroleum County had the lowest, at 52.9%. The median was 57.1% and the figure for Montana was 60.7%. Source: the U.S. Census Bureau.

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Highest68Gallatin County
Lowest52.9Petroleum County
Median57.156 counties
Montana60.7History

Map of counties, 2015

Beaverhead County: 59.7 %Big Horn County: 55.5 %Blaine County: 56.1 %Broadwater County: 56.5 %Carbon County: 58.4 %Carter County: 56 %Cascade County: 60.4 %Chouteau County: 56.1 %Custer County: 58.3 %Daniels County: 55.2 %Dawson County: 60.4 %Deer Lodge County: 60.7 %Fallon County: 57.7 %Fergus County: 55.6 %Flathead County: 59.3 %Gallatin County: 68 %Garfield County: 53.2 %Glacier County: 57.4 %Golden Valley County: 54.4 %Granite County: 54.3 %Hill County: 59 %Jefferson County: 59.6 %Judith Basin County: 58.8 %Lake County: 54.6 %Lewis and Clark County: 61.5 %Liberty County: 56.7 %Lincoln County: 55.6 %McCone County: 58.1 %Madison County: 57.1 %Meagher County: 57 %Mineral County: 56.2 %Missoula County: 65.7 %Musselshell County: 56.8 %Park County: 61.1 %Petroleum County: 52.9 %Phillips County: 56 %Pondera County: 55.5 %Powder River County: 58 %Powell County: 64.7 %Prairie County: 54.3 %Ravalli County: 55.5 %Richland County: 61.8 %Roosevelt County: 57.8 %Rosebud County: 57.7 %Sanders County: 54 %Sheridan County: 58.1 %Silver Bow County: 61.8 %Stillwater County: 58 %Sweet Grass County: 54.1 %Teton County: 54.6 %Toole County: 65.8 %Treasure County: 55.4 %Valley County: 56.1 %Wheatland County: 54.2 %Wibaux County: 53.9 %Yellowstone County: 60.7 %
  • Under 55
  • 55 to 56
  • 56 to 57
  • 57 to 58
  • 58 to 61
  • 61 and over
%, 2015. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2015

Gallatin County: 68 %Gallatin County68Toole County: 65.8 %Toole County65.8Missoula County: 65.7 %Missoula County65.7Powell County: 64.7 %Powell County64.7Silver Bow County: 61.8 %Silver Bow County61.8Richland County: 61.8 %Richland County61.8Lewis and Clark County: 61.5 %Lewis and Clark County61.5Park County: 61.1 %Park County61.1Deer Lodge County: 60.7 %Deer Lodge County60.7Yellowstone County: 60.7 %Yellowstone County60.7Cascade County: 60.4 %Cascade County60.4Dawson County: 60.4 %Dawson County60.4Beaverhead County: 59.7 %Beaverhead County59.7Jefferson County: 59.6 %Jefferson County59.6Flathead County: 59.3 %Flathead County59.3Hill County: 59 %Hill County59Judith Basin County: 58.8 %Judith Basin County58.8Carbon County: 58.4 %Carbon County58.4Custer County: 58.3 %Custer County58.3Sheridan County: 58.1 %Sheridan County58.1McCone County: 58.1 %McCone County58.1Powder River County: 58 %Powder River County58Stillwater County: 58 %Stillwater County58Roosevelt County: 57.8 %Roosevelt County57.8Fallon County: 57.7 %Fallon County57.7Rosebud County: 57.7 %Rosebud County57.7Glacier County: 57.4 %Glacier County57.4Madison County: 57.1 %Madison County57.1Meagher County: 57 %Meagher County57Musselshell County: 56.8 %Musselshell County56.8Liberty County: 56.7 %Liberty County56.7Broadwater County: 56.5 %Broadwater County56.5Mineral County: 56.2 %Mineral County56.2Chouteau County: 56.1 %Chouteau County56.1Valley County: 56.1 %Valley County56.1Blaine County: 56.1 %Blaine County56.1Phillips County: 56 %Phillips County56Carter County: 56 %Carter County56Lincoln County: 55.6 %Lincoln County55.6Fergus County: 55.6 %Fergus County55.6Ravalli County: 55.5 %Ravalli County55.5Big Horn County: 55.5 %Big Horn County55.5Pondera County: 55.5 %Pondera County55.5Treasure County: 55.4 %Treasure County55.4Daniels County: 55.2 %Daniels County55.2Teton County: 54.6 %Teton County54.6Lake County: 54.6 %Lake County54.6Golden Valley County: 54.4 %Golden Valley County54.4Prairie County: 54.3 %Prairie County54.3Granite County: 54.3 %Granite County54.3Wheatland County: 54.2 %Wheatland County54.2Sweet Grass County: 54.1 %Sweet Grass County54.1Sanders County: 54 %Sanders County54Wibaux County: 53.9 %Wibaux County53.9Garfield County: 53.2 %Garfield County53.2Petroleum County: 52.9 %Petroleum County52.9Gallatin County: 68 %Gallatin County68Toole County: 65.8 %Toole County65.8Missoula County: 65.7 %Missoula County65.7Powell County: 64.7 %Powell County64.7Silver Bow County: 61.8 %Silver Bow County61.8Richland County: 61.8 %Richland County61.8Lewis and Clark County: 61.5 %Lewis and Clark County61.5Park County: 61.1 %Park County61.1Deer Lodge County: 60.7 %Deer Lodge County60.7Yellowstone County: 60.7 %Yellowstone County60.7Cascade County: 60.4 %Cascade County60.4Dawson County: 60.4 %Dawson County60.4Beaverhead County: 59.7 %Beaverhead County59.7Jefferson County: 59.6 %Jefferson County59.6Flathead County: 59.3 %Flathead County59.3Hill County: 59 %Hill County59Judith Basin County: 58.8 %Judith Basin County58.8Carbon County: 58.4 %Carbon County58.4Custer County: 58.3 %Custer County58.3Sheridan County: 58.1 %Sheridan County58.1McCone County: 58.1 %McCone County58.1Powder River County: 58 %Powder River County58Stillwater County: 58 %Stillwater County58Roosevelt County: 57.8 %Roosevelt County57.8Fallon County: 57.7 %Fallon County57.7Rosebud County: 57.7 %Rosebud County57.7Glacier County: 57.4 %Glacier County57.4Madison County: 57.1 %Madison County57.1Meagher County: 57 %Meagher County57Musselshell County: 56.8 %Musselshell County56.8Liberty County: 56.7 %Liberty County56.7Broadwater County: 56.5 %Broadwater County56.5Mineral County: 56.2 %Mineral County56.2Chouteau County: 56.1 %Chouteau County56.1Valley County: 56.1 %Valley County56.1Blaine County: 56.1 %Blaine County56.1Phillips County: 56 %Phillips County56Carter County: 56 %Carter County56Lincoln County: 55.6 %Lincoln County55.6Fergus County: 55.6 %Fergus County55.6Ravalli County: 55.5 %Ravalli County55.5Big Horn County: 55.5 %Big Horn County55.5Pondera County: 55.5 %Pondera County55.5Treasure County: 55.4 %Treasure County55.4Daniels County: 55.2 %Daniels County55.2Teton County: 54.6 %Teton County54.6Lake County: 54.6 %Lake County54.6Golden Valley County: 54.4 %Golden Valley County54.4Prairie County: 54.3 %Prairie County54.3Granite County: 54.3 %Granite County54.3Wheatland County: 54.2 %Wheatland County54.2Sweet Grass County: 54.1 %Sweet Grass County54.1Sanders County: 54 %Sanders County54Wibaux County: 53.9 %Wibaux County53.9Garfield County: 53.2 %Garfield County53.2Petroleum County: 52.9 %Petroleum County52.9
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2015 (%)Change on 2014
1Gallatin County68-0.2 pts
2Toole County65.8+0.3 pts
3Missoula County65.7-0.6 pts
4Powell County64.7-0.7 pts
5Silver Bow County61.8-0.2 pts
6Richland County61.8-0.4 pts
7Lewis and Clark County61.5-0.5 pts
8Park County61.1-0.5 pts
9Deer Lodge County60.7-1 pts
10Yellowstone County60.7-0.4 pts
11Cascade County60.4-0.4 pts
12Dawson County60.4-0.4 pts
13Beaverhead County59.7-0.7 pts
14Jefferson County59.6-0.4 pts
15Flathead County59.3-0.5 pts
16Hill County59-0.6 pts
17Judith Basin County58.8-0.8 pts
18Carbon County58.4-0.7 pts
19Custer County58.3-0.6 pts
20Sheridan County58.1-0.6 pts
21McCone County58.1+0.5 pts
22Powder River County58-0.7 pts
23Stillwater County58-0.7 pts
24Roosevelt County57.8-0.2 pts
25Fallon County57.7-0.9 pts
26Rosebud County57.7-0.2 pts
27Glacier County57.4-0.5 pts
28Madison County57.1-1.2 pts
29Meagher County57+0.6 pts
30Musselshell County56.8-1.7 pts
31Liberty County56.7-1.3 pts
32Broadwater County56.5-1.1 pts
33Mineral County56.2-0.4 pts
34Chouteau County56.1+0.1 pts
35Valley County56.1-0.5 pts
36Blaine County56.1-0.2 pts
37Phillips County56-0.7 pts
38Carter County56-1.1 pts
39Lincoln County55.6-0.8 pts
40Fergus County55.6-1 pts
41Ravalli County55.5-0.6 pts
42Big Horn County55.5-0.1 pts
43Pondera County55.5-0.1 pts
44Treasure County55.4-0 pts
45Daniels County55.2+1.1 pts
46Teton County54.6-0.5 pts
47Lake County54.6-0.7 pts
48Golden Valley County54.4-2.6 pts
49Prairie County54.3+0.8 pts
50Granite County54.3-1.4 pts
51Wheatland County54.20 pts
52Sweet Grass County54.1-0.5 pts
53Sanders County54-1 pts
54Wibaux County53.9-1.4 pts
55Garfield County53.2-1.4 pts
56Petroleum County52.9-1.5 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, 2015) [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, 2015. 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=2015. 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, 2015. 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=2015.

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, 2015 [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=2015 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_montana_by_2015,
  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, 2015}},
  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=2015. 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, 2015
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=2015
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/montana-counties?period=2015.
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 68% in 2015, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Petroleum County, with 52.9% in 2015.

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