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 2016, at 67.8%. Garfield County had the lowest, at 52.6%. The median was 56.5% and the figure for Montana was 60.2%. Source: the U.S. Census Bureau.

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Highest67.8Gallatin County
Lowest52.6Garfield County
Median56.556 counties
Montana60.2History

Map of counties, 2016

Beaverhead County: 59 %Big Horn County: 54.8 %Blaine County: 56 %Broadwater County: 56.2 %Carbon County: 57.4 %Carter County: 55.8 %Cascade County: 60 %Chouteau County: 55.4 %Custer County: 58.4 %Daniels County: 53.7 %Dawson County: 59.3 %Deer Lodge County: 60.6 %Fallon County: 57.2 %Fergus County: 54.9 %Flathead County: 58.9 %Gallatin County: 67.8 %Garfield County: 52.6 %Glacier County: 57.2 %Golden Valley County: 53.7 %Granite County: 55 %Hill County: 58.7 %Jefferson County: 58.5 %Judith Basin County: 57.6 %Lake County: 54.2 %Lewis and Clark County: 60.8 %Liberty County: 56.8 %Lincoln County: 54.5 %McCone County: 57.2 %Madison County: 56.4 %Meagher County: 56 %Mineral County: 55.1 %Missoula County: 65.1 %Musselshell County: 56.4 %Park County: 60.8 %Petroleum County: 54.7 %Phillips County: 55.6 %Pondera County: 55.4 %Powder River County: 57.5 %Powell County: 64.2 %Prairie County: 53.2 %Ravalli County: 55 %Richland County: 61.2 %Roosevelt County: 56.6 %Rosebud County: 56.8 %Sanders County: 53.1 %Sheridan County: 57.4 %Silver Bow County: 61.2 %Stillwater County: 57.7 %Sweet Grass County: 54.4 %Teton County: 54.5 %Toole County: 65.5 %Treasure County: 55.5 %Valley County: 55.3 %Wheatland County: 53.6 %Wibaux County: 52.9 %Yellowstone County: 60.3 %
  • Under 54
  • 54 to 55
  • 55 to 57
  • 57 to 58
  • 58 to 60
  • 60 and over
%, 2016. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2016

Gallatin County: 67.8 %Gallatin County67.8Toole County: 65.5 %Toole County65.5Missoula County: 65.1 %Missoula County65.1Powell County: 64.2 %Powell County64.2Silver Bow County: 61.2 %Silver Bow County61.2Richland County: 61.2 %Richland County61.2Lewis and Clark County: 60.8 %Lewis and Clark County60.8Park County: 60.8 %Park County60.8Deer Lodge County: 60.6 %Deer Lodge County60.6Yellowstone County: 60.3 %Yellowstone County60.3Cascade County: 60 %Cascade County60Dawson County: 59.3 %Dawson County59.3Beaverhead County: 59 %Beaverhead County59Flathead County: 58.9 %Flathead County58.9Hill County: 58.7 %Hill County58.7Jefferson County: 58.5 %Jefferson County58.5Custer County: 58.4 %Custer County58.4Stillwater County: 57.7 %Stillwater County57.7Judith Basin County: 57.6 %Judith Basin County57.6Powder River County: 57.5 %Powder River County57.5Carbon County: 57.4 %Carbon County57.4Sheridan County: 57.4 %Sheridan County57.4McCone County: 57.2 %McCone County57.2Glacier County: 57.2 %Glacier County57.2Fallon County: 57.2 %Fallon County57.2Rosebud County: 56.8 %Rosebud County56.8Liberty County: 56.8 %Liberty County56.8Roosevelt County: 56.6 %Roosevelt County56.6Musselshell County: 56.4 %Musselshell County56.4Madison County: 56.4 %Madison County56.4Broadwater County: 56.2 %Broadwater County56.2Meagher County: 56 %Meagher County56Blaine County: 56 %Blaine County56Carter County: 55.8 %Carter County55.8Phillips County: 55.6 %Phillips County55.6Treasure County: 55.5 %Treasure County55.5Chouteau County: 55.4 %Chouteau County55.4Pondera County: 55.4 %Pondera County55.4Valley County: 55.3 %Valley County55.3Mineral County: 55.1 %Mineral County55.1Granite County: 55 %Granite County55Ravalli County: 55 %Ravalli County55Fergus County: 54.9 %Fergus County54.9Big Horn County: 54.8 %Big Horn County54.8Petroleum County: 54.7 %Petroleum County54.7Lincoln County: 54.5 %Lincoln County54.5Teton County: 54.5 %Teton County54.5Sweet Grass County: 54.4 %Sweet Grass County54.4Lake County: 54.2 %Lake County54.2Daniels County: 53.7 %Daniels County53.7Golden Valley County: 53.7 %Golden Valley County53.7Wheatland County: 53.6 %Wheatland County53.6Prairie County: 53.2 %Prairie County53.2Sanders County: 53.1 %Sanders County53.1Wibaux County: 52.9 %Wibaux County52.9Garfield County: 52.6 %Garfield County52.6Gallatin County: 67.8 %Gallatin County67.8Toole County: 65.5 %Toole County65.5Missoula County: 65.1 %Missoula County65.1Powell County: 64.2 %Powell County64.2Silver Bow County: 61.2 %Silver Bow County61.2Richland County: 61.2 %Richland County61.2Lewis and Clark County: 60.8 %Lewis and Clark County60.8Park County: 60.8 %Park County60.8Deer Lodge County: 60.6 %Deer Lodge County60.6Yellowstone County: 60.3 %Yellowstone County60.3Cascade County: 60 %Cascade County60Dawson County: 59.3 %Dawson County59.3Beaverhead County: 59 %Beaverhead County59Flathead County: 58.9 %Flathead County58.9Hill County: 58.7 %Hill County58.7Jefferson County: 58.5 %Jefferson County58.5Custer County: 58.4 %Custer County58.4Stillwater County: 57.7 %Stillwater County57.7Judith Basin County: 57.6 %Judith Basin County57.6Powder River County: 57.5 %Powder River County57.5Carbon County: 57.4 %Carbon County57.4Sheridan County: 57.4 %Sheridan County57.4McCone County: 57.2 %McCone County57.2Glacier County: 57.2 %Glacier County57.2Fallon County: 57.2 %Fallon County57.2Rosebud County: 56.8 %Rosebud County56.8Liberty County: 56.8 %Liberty County56.8Roosevelt County: 56.6 %Roosevelt County56.6Musselshell County: 56.4 %Musselshell County56.4Madison County: 56.4 %Madison County56.4Broadwater County: 56.2 %Broadwater County56.2Meagher County: 56 %Meagher County56Blaine County: 56 %Blaine County56Carter County: 55.8 %Carter County55.8Phillips County: 55.6 %Phillips County55.6Treasure County: 55.5 %Treasure County55.5Chouteau County: 55.4 %Chouteau County55.4Pondera County: 55.4 %Pondera County55.4Valley County: 55.3 %Valley County55.3Mineral County: 55.1 %Mineral County55.1Granite County: 55 %Granite County55Ravalli County: 55 %Ravalli County55Fergus County: 54.9 %Fergus County54.9Big Horn County: 54.8 %Big Horn County54.8Petroleum County: 54.7 %Petroleum County54.7Lincoln County: 54.5 %Lincoln County54.5Teton County: 54.5 %Teton County54.5Sweet Grass County: 54.4 %Sweet Grass County54.4Lake County: 54.2 %Lake County54.2Daniels County: 53.7 %Daniels County53.7Golden Valley County: 53.7 %Golden Valley County53.7Wheatland County: 53.6 %Wheatland County53.6Prairie County: 53.2 %Prairie County53.2Sanders County: 53.1 %Sanders County53.1Wibaux County: 52.9 %Wibaux County52.9Garfield County: 52.6 %Garfield County52.6
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2016 (%)Change on 2015
1Gallatin County67.8-0.3 pts
2Toole County65.5-0.3 pts
3Missoula County65.1-0.6 pts
4Powell County64.2-0.5 pts
5Silver Bow County61.2-0.6 pts
6Richland County61.2-0.7 pts
7Lewis and Clark County60.8-0.7 pts
8Park County60.8-0.3 pts
9Deer Lodge County60.6-0.1 pts
10Yellowstone County60.3-0.5 pts
11Cascade County60-0.4 pts
12Dawson County59.3-1.1 pts
13Beaverhead County59-0.7 pts
14Flathead County58.9-0.4 pts
15Hill County58.7-0.3 pts
16Jefferson County58.5-1.1 pts
17Custer County58.4+0.1 pts
18Stillwater County57.7-0.3 pts
19Judith Basin County57.6-1.2 pts
20Powder River County57.5-0.5 pts
21Carbon County57.4-1 pts
22Sheridan County57.4-0.7 pts
23McCone County57.2-0.9 pts
24Glacier County57.2-0.2 pts
25Fallon County57.2-0.5 pts
26Rosebud County56.8-0.8 pts
27Liberty County56.8+0.1 pts
28Roosevelt County56.6-1.2 pts
29Musselshell County56.4-0.3 pts
30Madison County56.4-0.8 pts
31Broadwater County56.2-0.3 pts
32Meagher County56-1 pts
33Blaine County56-0.1 pts
34Carter County55.8-0.2 pts
35Phillips County55.6-0.5 pts
36Treasure County55.5+0.1 pts
37Chouteau County55.4-0.7 pts
38Pondera County55.4-0 pts
39Valley County55.3-0.8 pts
40Mineral County55.1-1 pts
41Granite County55+0.7 pts
42Ravalli County55-0.6 pts
43Fergus County54.9-0.7 pts
44Big Horn County54.8-0.7 pts
45Petroleum County54.7+1.7 pts
46Lincoln County54.5-1.1 pts
47Teton County54.5-0.2 pts
48Sweet Grass County54.4+0.3 pts
49Lake County54.2-0.4 pts
50Daniels County53.7-1.5 pts
51Golden Valley County53.7-0.7 pts
52Wheatland County53.6-0.6 pts
53Prairie County53.2-1.1 pts
54Sanders County53.1-1 pts
55Wibaux County52.9-1 pts
56Garfield County52.6-0.7 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, 2016) [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, 2016. 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=2016. 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, 2016. 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=2016.

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, 2016 [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=2016 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_montana_by_2016,
  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, 2016}},
  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=2016. 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, 2016
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=2016
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/montana-counties?period=2016.
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 67.8% in 2016, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Garfield County, with 52.6% in 2016.

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