Data / Rankings / Population under 18 / Counties in Montana

Counties in Montana by population under 18

Roosevelt County had the highest population under 18 of 56 counties in 2022, at 32.3%. Powell County had the lowest, at 14.8%. The median was 21% and the figure for Montana was 21.1%. Source: the U.S. Census Bureau.

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Highest32.3Roosevelt County
Lowest14.8Powell County
Median2156 counties
Montana21.1History

Map of counties, 2022

Beaverhead County: 18.4 %Big Horn County: 31.8 %Blaine County: 28.1 %Broadwater County: 21.5 %Carbon County: 18.4 %Carter County: 21.6 %Cascade County: 22 %Chouteau County: 22.9 %Custer County: 21.9 %Daniels County: 21 %Dawson County: 21.3 %Deer Lodge County: 15 %Fallon County: 26.4 %Fergus County: 20.7 %Flathead County: 21.9 %Gallatin County: 18.9 %Garfield County: 24.9 %Glacier County: 30 %Golden Valley County: 18.8 %Granite County: 16.4 %Hill County: 27.4 %Jefferson County: 20.8 %Judith Basin County: 18.8 %Lake County: 22.1 %Lewis and Clark County: 21.1 %Liberty County: 24.5 %Lincoln County: 18.3 %McCone County: 20.2 %Madison County: 16.1 %Meagher County: 17.5 %Mineral County: 18.8 %Missoula County: 18.7 %Musselshell County: 21.4 %Park County: 16.7 %Petroleum County: 14.8 %Phillips County: 23.9 %Pondera County: 24.3 %Powder River County: 19.1 %Powell County: 14.8 %Prairie County: 20.5 %Ravalli County: 19.1 %Richland County: 23.9 %Roosevelt County: 32.3 %Rosebud County: 28.5 %Sanders County: 17.1 %Sheridan County: 21.2 %Silver Bow County: 19.7 %Stillwater County: 20.8 %Sweet Grass County: 19.4 %Teton County: 23.4 %Toole County: 20.5 %Treasure County: 21.5 %Valley County: 22.6 %Wheatland County: 22 %Wibaux County: 20.5 %Yellowstone County: 22.7 %
  • Under 18
  • 18 to 19
  • 19 to 21
  • 21 to 22
  • 22 to 24
  • 24 and over
%, 2022. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2022

Roosevelt County: 32.3 %Roosevelt County32.3Big Horn County: 31.8 %Big Horn County31.8Glacier County: 30 %Glacier County30Rosebud County: 28.5 %Rosebud County28.5Blaine County: 28.1 %Blaine County28.1Hill County: 27.4 %Hill County27.4Fallon County: 26.4 %Fallon County26.4Garfield County: 24.9 %Garfield County24.9Liberty County: 24.5 %Liberty County24.5Pondera County: 24.3 %Pondera County24.3Phillips County: 23.9 %Phillips County23.9Richland County: 23.9 %Richland County23.9Teton County: 23.4 %Teton County23.4Chouteau County: 22.9 %Chouteau County22.9Yellowstone County: 22.7 %Yellowstone County22.7Valley County: 22.6 %Valley County22.6Lake County: 22.1 %Lake County22.1Cascade County: 22 %Cascade County22Wheatland County: 22 %Wheatland County22Flathead County: 21.9 %Flathead County21.9Custer County: 21.9 %Custer County21.9Carter County: 21.6 %Carter County21.6Treasure County: 21.5 %Treasure County21.5Broadwater County: 21.5 %Broadwater County21.5Musselshell County: 21.4 %Musselshell County21.4Dawson County: 21.3 %Dawson County21.3Sheridan County: 21.2 %Sheridan County21.2Lewis and Clark County: 21.1 %Lewis and Clark County21.1Daniels County: 21 %Daniels County21Jefferson County: 20.8 %Jefferson County20.8Stillwater County: 20.8 %Stillwater County20.8Fergus County: 20.7 %Fergus County20.7Wibaux County: 20.5 %Wibaux County20.5Prairie County: 20.5 %Prairie County20.5Toole County: 20.5 %Toole County20.5McCone County: 20.2 %McCone County20.2Silver Bow County: 19.7 %Silver Bow County19.7Sweet Grass County: 19.4 %Sweet Grass County19.4Powder River County: 19.1 %Powder River County19.1Ravalli County: 19.1 %Ravalli County19.1Gallatin County: 18.9 %Gallatin County18.9Mineral County: 18.8 %Mineral County18.8Judith Basin County: 18.8 %Judith Basin County18.8Golden Valley County: 18.8 %Golden Valley County18.8Missoula County: 18.7 %Missoula County18.7Carbon County: 18.4 %Carbon County18.4Beaverhead County: 18.4 %Beaverhead County18.4Lincoln County: 18.3 %Lincoln County18.3Meagher County: 17.5 %Meagher County17.5Sanders County: 17.1 %Sanders County17.1Park County: 16.7 %Park County16.7Granite County: 16.4 %Granite County16.4Madison County: 16.1 %Madison County16.1Deer Lodge County: 15 %Deer Lodge County15Petroleum County: 14.8 %Petroleum County14.8Powell County: 14.8 %Powell County14.8Roosevelt County: 32.3 %Roosevelt County32.3Big Horn County: 31.8 %Big Horn County31.8Glacier County: 30 %Glacier County30Rosebud County: 28.5 %Rosebud County28.5Blaine County: 28.1 %Blaine County28.1Hill County: 27.4 %Hill County27.4Fallon County: 26.4 %Fallon County26.4Garfield County: 24.9 %Garfield County24.9Liberty County: 24.5 %Liberty County24.5Pondera County: 24.3 %Pondera County24.3Phillips County: 23.9 %Phillips County23.9Richland County: 23.9 %Richland County23.9Teton County: 23.4 %Teton County23.4Chouteau County: 22.9 %Chouteau County22.9Yellowstone County: 22.7 %Yellowstone County22.7Valley County: 22.6 %Valley County22.6Lake County: 22.1 %Lake County22.1Cascade County: 22 %Cascade County22Wheatland County: 22 %Wheatland County22Flathead County: 21.9 %Flathead County21.9Custer County: 21.9 %Custer County21.9Carter County: 21.6 %Carter County21.6Treasure County: 21.5 %Treasure County21.5Broadwater County: 21.5 %Broadwater County21.5Musselshell County: 21.4 %Musselshell County21.4Dawson County: 21.3 %Dawson County21.3Sheridan County: 21.2 %Sheridan County21.2Lewis and Clark County: 21.1 %Lewis and Clark County21.1Daniels County: 21 %Daniels County21Jefferson County: 20.8 %Jefferson County20.8Stillwater County: 20.8 %Stillwater County20.8Fergus County: 20.7 %Fergus County20.7Wibaux County: 20.5 %Wibaux County20.5Prairie County: 20.5 %Prairie County20.5Toole County: 20.5 %Toole County20.5McCone County: 20.2 %McCone County20.2Silver Bow County: 19.7 %Silver Bow County19.7Sweet Grass County: 19.4 %Sweet Grass County19.4Powder River County: 19.1 %Powder River County19.1Ravalli County: 19.1 %Ravalli County19.1Gallatin County: 18.9 %Gallatin County18.9Mineral County: 18.8 %Mineral County18.8Judith Basin County: 18.8 %Judith Basin County18.8Golden Valley County: 18.8 %Golden Valley County18.8Missoula County: 18.7 %Missoula County18.7Carbon County: 18.4 %Carbon County18.4Beaverhead County: 18.4 %Beaverhead County18.4Lincoln County: 18.3 %Lincoln County18.3Meagher County: 17.5 %Meagher County17.5Sanders County: 17.1 %Sanders County17.1Park County: 16.7 %Park County16.7Granite County: 16.4 %Granite County16.4Madison County: 16.1 %Madison County16.1Deer Lodge County: 15 %Deer Lodge County15Petroleum County: 14.8 %Petroleum County14.8Powell County: 14.8 %Powell County14.8
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2022 (%)Change on 2021
1Roosevelt County32.3-0.4 pts
2Big Horn County31.8-0.7 pts
3Glacier County30-0.5 pts
4Rosebud County28.5+0.3 pts
5Blaine County28.1-1 pts
6Hill County27.4+0.1 pts
7Fallon County26.4+0.6 pts
8Garfield County24.9+0.3 pts
9Liberty County24.5+1.4 pts
10Pondera County24.3+0.7 pts
11Phillips County23.9+0.5 pts
12Richland County23.9-0.3 pts
13Teton County23.4+0.2 pts
14Chouteau County22.9-0.5 pts
15Yellowstone County22.7-0.2 pts
16Valley County22.6+0.2 pts
17Lake County22.1-0.4 pts
18Cascade County22-0.2 pts
19Wheatland County22-0.5 pts
20Flathead County21.90 pts
21Custer County21.9-0.1 pts
22Carter County21.6-0.3 pts
23Treasure County21.5-0.3 pts
24Broadwater County21.5+0.5 pts
25Musselshell County21.4+1.1 pts
26Dawson County21.3-0.2 pts
27Sheridan County21.2+0.2 pts
28Lewis and Clark County21.1-0.2 pts
29Daniels County21-0.8 pts
30Jefferson County20.8+0.4 pts
31Stillwater County20.8-0 pts
32Fergus County20.7-0.1 pts
33Wibaux County20.5+0.2 pts
34Prairie County20.5+0.8 pts
35Toole County20.5+0.3 pts
36McCone County20.2-0.4 pts
37Silver Bow County19.7-0.3 pts
38Sweet Grass County19.4-0.2 pts
39Powder River County19.1+0.4 pts
40Ravalli County19.1-0 pts
41Gallatin County18.9-0.3 pts
42Mineral County18.8-0.3 pts
43Judith Basin County18.8-0.7 pts
44Golden Valley County18.8+0.7 pts
45Missoula County18.7-0.3 pts
46Carbon County18.4+0.1 pts
47Beaverhead County18.4-0.4 pts
48Lincoln County18.3-0.3 pts
49Meagher County17.5+0.4 pts
50Sanders County17.1+0.2 pts
51Park County16.7-0.2 pts
52Granite County16.4-1.3 pts
53Madison County16.10 pts
54Deer Lodge County15-0.3 pts
55Petroleum County14.8+0.5 pts
56Powell County14.8+0.4 pts

Other periods

About this ranking

Residents aged 0 to 17 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.

Uses the US age of majority. Not comparable with population_0_14_share, which stops at 14.

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 0 to 17 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 0 to 17 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 under 18, 2022) [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 0 to 17 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 under 18, 2022. U.S. Census Bureau, 25 June 2026, https://www.census.gov/programs-surveys/popest/data/data-sets.html. Invokely, https://invokely.ai/rankings/population-under-18/montana-counties?period=2022. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Census Bureau. 2026. Population Estimates Program, county population by age and sex: residents aged 0 to 17 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 under 18, 2022. 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-under-18/montana-counties?period=2022.

Harvard

U.S. Census Bureau (2026) Population Estimates Program, county population by age and sex: residents aged 0 to 17 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 under 18, 2022 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/population-under-18/montana-counties?period=2022 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_montana_by_2022,
  author = {{U.S. Census Bureau}},
  title = {{Population Estimates Program, county population by age and sex: residents aged 0 to 17 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 under 18, 2022}},
  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-under-18/montana-counties?period=2022. Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 0 to 17 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 0 to 17 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 under 18, 2022
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-under-18/montana-counties?period=2022
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-under-18/montana-counties?period=2022.
N1  - Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 0 to 17 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 under 18?

Roosevelt County, with 32.3% in 2022, according to the U.S. Census Bureau.

Which county has the lowest population under 18?

Powell County, with 14.8% in 2022.

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 0 to 17 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 under 18: other rankings

Counties in Montana: more rankings