Data / Rankings / Population under 18 / Counties in Colorado

Counties in Colorado by population under 18, 2025

Yuma County had the highest population under 18 of 64 counties in 2025, at 27.2%. Crowley County had the lowest, at 10%. The median was 18.6% and the figure for Colorado was 20.3%. Source: the U.S. Census Bureau.

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Highest27.2Yuma County
Lowest10Crowley County
Median18.664 counties
Colorado20.3History

Map of counties, 2025

Adams County: 23.3 %Alamosa County: 23.1 %Arapahoe County: 22.1 %Archuleta County: 16.9 %Baca County: 22 %Bent County: 14.7 %Boulder County: 16.3 %Broomfield County: 18.7 %Chaffee County: 14.7 %Cheyenne County: 24.8 %Clear Creek County: 11.8 %Conejos County: 26 %Costilla County: 18.6 %Crowley County: 10 %Custer County: 16 %Delta County: 18.7 %Denver County: 18.3 %Dolores County: 16.7 %Douglas County: 22.3 %Eagle County: 18.8 %Elbert County: 21.3 %El Paso County: 22.2 %Fremont County: 14.8 %Garfield County: 22.8 %Gilpin County: 12.7 %Grand County: 14.9 %Gunnison County: 15.5 %Hinsdale County: 15.3 %Huerfano County: 14.5 %Jackson County: 15.9 %Jefferson County: 17.5 %Kiowa County: 24.7 %Kit Carson County: 24.9 %Lake County: 20.3 %La Plata County: 16.8 %Larimer County: 17.4 %Las Animas County: 16.5 %Lincoln County: 20.3 %Logan County: 18.4 %Mesa County: 19 %Mineral County: 11.4 %Moffat County: 22.8 %Montezuma County: 20.3 %Montrose County: 19.2 %Morgan County: 26.4 %Otero County: 22.3 %Ouray County: 12.6 %Park County: 14.8 %Phillips County: 24.6 %Pitkin County: 15.5 %Prowers County: 25.4 %Pueblo County: 21 %Rio Blanco County: 21.4 %Rio Grande County: 19.9 %Routt County: 17.6 %Saguache County: 18.1 %San Juan County: 11.6 %San Miguel County: 15.8 %Sedgwick County: 19.5 %Summit County: 15.9 %Teller County: 15.6 %Washington County: 22.5 %Weld County: 25.1 %Yuma County: 27.2 %
  • Under 15
  • 15 to 17
  • 17 to 19
  • 19 to 21
  • 21 to 23
  • 23 and over
%, 2025. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

Top 40 counties, 2025

Yuma County: 27.2 %Yuma County27.2Morgan County: 26.4 %Morgan County26.4Conejos County: 26 %Conejos County26Prowers County: 25.4 %Prowers County25.4Weld County: 25.1 %Weld County25.1Kit Carson County: 24.9 %Kit Carson County24.9Cheyenne County: 24.8 %Cheyenne County24.8Kiowa County: 24.7 %Kiowa County24.7Phillips County: 24.6 %Phillips County24.6Adams County: 23.3 %Adams County23.3Alamosa County: 23.1 %Alamosa County23.1Garfield County: 22.8 %Garfield County22.8Moffat County: 22.8 %Moffat County22.8Washington County: 22.5 %Washington County22.5Douglas County: 22.3 %Douglas County22.3Otero County: 22.3 %Otero County22.3El Paso County: 22.2 %El Paso County22.2Arapahoe County: 22.1 %Arapahoe County22.1Baca County: 22 %Baca County22Rio Blanco County: 21.4 %Rio Blanco County21.4Elbert County: 21.3 %Elbert County21.3Pueblo County: 21 %Pueblo County21Montezuma County: 20.3 %Montezuma County20.3Lincoln County: 20.3 %Lincoln County20.3Lake County: 20.3 %Lake County20.3Rio Grande County: 19.9 %Rio Grande County19.9Sedgwick County: 19.5 %Sedgwick County19.5Montrose County: 19.2 %Montrose County19.2Mesa County: 19 %Mesa County19Eagle County: 18.8 %Eagle County18.8Delta County: 18.7 %Delta County18.7Broomfield County: 18.7 %Broomfield County18.7Costilla County: 18.6 %Costilla County18.6Logan County: 18.4 %Logan County18.4Denver County: 18.3 %Denver County18.3Saguache County: 18.1 %Saguache County18.1Routt County: 17.6 %Routt County17.6Jefferson County: 17.5 %Jefferson County17.5Larimer County: 17.4 %Larimer County17.4Archuleta County: 16.9 %Archuleta County16.9Yuma County: 27.2 %Yuma County27.2Morgan County: 26.4 %Morgan County26.4Conejos County: 26 %Conejos County26Prowers County: 25.4 %Prowers County25.4Weld County: 25.1 %Weld County25.1Kit Carson County: 24.9 %Kit Carson County24.9Cheyenne County: 24.8 %Cheyenne County24.8Kiowa County: 24.7 %Kiowa County24.7Phillips County: 24.6 %Phillips County24.6Adams County: 23.3 %Adams County23.3Alamosa County: 23.1 %Alamosa County23.1Garfield County: 22.8 %Garfield County22.8Moffat County: 22.8 %Moffat County22.8Washington County: 22.5 %Washington County22.5Douglas County: 22.3 %Douglas County22.3Otero County: 22.3 %Otero County22.3El Paso County: 22.2 %El Paso County22.2Arapahoe County: 22.1 %Arapahoe County22.1Baca County: 22 %Baca County22Rio Blanco County: 21.4 %Rio Blanco County21.4Elbert County: 21.3 %Elbert County21.3Pueblo County: 21 %Pueblo County21Montezuma County: 20.3 %Montezuma County20.3Lincoln County: 20.3 %Lincoln County20.3Lake County: 20.3 %Lake County20.3Rio Grande County: 19.9 %Rio Grande County19.9Sedgwick County: 19.5 %Sedgwick County19.5Montrose County: 19.2 %Montrose County19.2Mesa County: 19 %Mesa County19Eagle County: 18.8 %Eagle County18.8Delta County: 18.7 %Delta County18.7Broomfield County: 18.7 %Broomfield County18.7Costilla County: 18.6 %Costilla County18.6Logan County: 18.4 %Logan County18.4Denver County: 18.3 %Denver County18.3Saguache County: 18.1 %Saguache County18.1Routt County: 17.6 %Routt County17.6Jefferson County: 17.5 %Jefferson County17.5Larimer County: 17.4 %Larimer County17.4Archuleta County: 16.9 %Archuleta County16.9
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2025 (%)Change on 2024
1Yuma County27.2-0.2 pts
2Morgan County26.4+0.1 pts
3Conejos County26-0.4 pts
4Prowers County25.4-0.1 pts
5Weld County25.1-0.3 pts
6Kit Carson County24.9-0 pts
7Cheyenne County24.8-0.5 pts
8Kiowa County24.7-0.4 pts
9Phillips County24.6-0.3 pts
10Adams County23.3-0.3 pts
11Alamosa County23.1-0.2 pts
12Garfield County22.8-0.3 pts
13Moffat County22.8-0.5 pts
14Washington County22.5-0 pts
15Douglas County22.3-0.6 pts
16Otero County22.3-0.5 pts
17El Paso County22.2-0.2 pts
18Arapahoe County22.1-0.1 pts
19Baca County22+0.1 pts
20Rio Blanco County21.4-0.8 pts
21Elbert County21.3-0.1 pts
22Pueblo County21-0.3 pts
23Montezuma County20.3-0.1 pts
24Lincoln County20.3+0.5 pts
25Lake County20.3-0.4 pts
26Rio Grande County19.9-0.2 pts
27Sedgwick County19.5+0.3 pts
28Montrose County19.2-0.3 pts
29Mesa County19-0.4 pts
30Eagle County18.8-0.4 pts
31Delta County18.7-0.3 pts
32Broomfield County18.7-0.5 pts
33Costilla County18.6+0.4 pts
34Logan County18.4-0.2 pts
35Denver County18.3+0.1 pts
36Saguache County18.1-0.1 pts
37Routt County17.6-0.2 pts
38Jefferson County17.5-0.3 pts
39Larimer County17.4-0.3 pts
40Archuleta County16.9-0.1 pts
41La Plata County16.8-0.3 pts
42Dolores County16.7+0.5 pts
43Las Animas County16.5-0.3 pts
44Boulder County16.3-0.4 pts
45Custer County16+0.2 pts
46Jackson County15.9-1.1 pts
47Summit County15.9-0.1 pts
48San Miguel County15.8-1 pts
49Teller County15.6-0.1 pts
50Gunnison County15.5-0.2 pts
51Pitkin County15.5-0.2 pts
52Hinsdale County15.3+1.2 pts
53Grand County14.9-0.1 pts
54Fremont County14.8-0.4 pts
55Park County14.8-0 pts
56Chaffee County14.7-0.2 pts
57Bent County14.7-0.7 pts
58Huerfano County14.5+0.3 pts
59Gilpin County12.7-0.2 pts
60Ouray County12.6+0.2 pts
61Clear Creek County11.8-0.2 pts
62San Juan County11.6-0.4 pts
63Mineral County11.4+0.9 pts
64Crowley County10-0.9 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 Colorado by population under 18, 2025) [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 Colorado by population under 18, 2025. 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/colorado-counties. 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 Colorado by population under 18, 2025. 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/colorado-counties.

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 Colorado by population under 18, 2025 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/population-under-18/colorado-counties (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_colorado_by_2025,
  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 Colorado by population under 18, 2025}},
  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/colorado-counties. 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 Colorado by population under 18, 2025
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/colorado-counties
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-under-18/colorado-counties.
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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Rank Counties in Colorado by population under 18 using official data, and cite the source.
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Questions

Which county has the highest population under 18?

Yuma County, with 27.2% in 2025, according to the U.S. Census Bureau.

Which county has the lowest population under 18?

Crowley County, with 10% in 2025.

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 Colorado: more rankings