Data / Rankings / Population under 18 / Counties in Colorado

Counties in Colorado by population under 18

Yuma County had the highest population under 18 of 64 counties in 2024, at 27.3%. Mineral County had the lowest, at 10.5%. The median was 18.8% and the figure for Colorado was 20.5%. Source: the U.S. Census Bureau.

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Highest27.3Yuma County
Lowest10.5Mineral County
Median18.864 counties
Colorado20.5History

Map of counties, 2024

Adams County: 23.6 %Alamosa County: 23.3 %Arapahoe County: 22.3 %Archuleta County: 17 %Baca County: 21.9 %Bent County: 15.4 %Boulder County: 16.7 %Broomfield County: 19.2 %Chaffee County: 14.9 %Cheyenne County: 25.3 %Clear Creek County: 12 %Conejos County: 26.4 %Costilla County: 18.2 %Crowley County: 10.9 %Custer County: 15.8 %Delta County: 19 %Denver County: 18.2 %Dolores County: 16.2 %Douglas County: 22.8 %Eagle County: 19.2 %Elbert County: 21.3 %El Paso County: 22.4 %Fremont County: 15.3 %Garfield County: 23.2 %Gilpin County: 12.9 %Grand County: 15 %Gunnison County: 15.7 %Hinsdale County: 14.1 %Huerfano County: 14.2 %Jackson County: 17 %Jefferson County: 17.8 %Kiowa County: 25.2 %Kit Carson County: 24.9 %Lake County: 20.7 %La Plata County: 17.1 %Larimer County: 17.7 %Las Animas County: 16.8 %Lincoln County: 19.8 %Logan County: 18.7 %Mesa County: 19.5 %Mineral County: 10.5 %Moffat County: 23.3 %Montezuma County: 20.5 %Montrose County: 19.5 %Morgan County: 26.3 %Otero County: 22.8 %Ouray County: 12.4 %Park County: 14.8 %Phillips County: 25 %Pitkin County: 15.7 %Prowers County: 25.5 %Pueblo County: 21.3 %Rio Blanco County: 22.2 %Rio Grande County: 20.1 %Routt County: 17.8 %Saguache County: 18.2 %San Juan County: 11.9 %San Miguel County: 16.8 %Sedgwick County: 19.2 %Summit County: 16 %Teller County: 15.7 %Washington County: 22.6 %Weld County: 25.4 %Yuma County: 27.3 %
  • Under 15
  • 15 to 17
  • 17 to 19
  • 19 to 21
  • 21 to 23
  • 23 and over
%, 2024. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

Top 40 counties, 2024

Yuma County: 27.3 %Yuma County27.3Conejos County: 26.4 %Conejos County26.4Morgan County: 26.3 %Morgan County26.3Prowers County: 25.5 %Prowers County25.5Weld County: 25.4 %Weld County25.4Cheyenne County: 25.3 %Cheyenne County25.3Kiowa County: 25.2 %Kiowa County25.2Phillips County: 25 %Phillips County25Kit Carson County: 24.9 %Kit Carson County24.9Adams County: 23.6 %Adams County23.6Alamosa County: 23.3 %Alamosa County23.3Moffat County: 23.3 %Moffat County23.3Garfield County: 23.2 %Garfield County23.2Douglas County: 22.8 %Douglas County22.8Otero County: 22.8 %Otero County22.8Washington County: 22.6 %Washington County22.6El Paso County: 22.4 %El Paso County22.4Arapahoe County: 22.3 %Arapahoe County22.3Rio Blanco County: 22.2 %Rio Blanco County22.2Baca County: 21.9 %Baca County21.9Elbert County: 21.3 %Elbert County21.3Pueblo County: 21.3 %Pueblo County21.3Lake County: 20.7 %Lake County20.7Montezuma County: 20.5 %Montezuma County20.5Rio Grande County: 20.1 %Rio Grande County20.1Lincoln County: 19.8 %Lincoln County19.8Montrose County: 19.5 %Montrose County19.5Mesa County: 19.5 %Mesa County19.5Eagle County: 19.2 %Eagle County19.2Broomfield County: 19.2 %Broomfield County19.2Sedgwick County: 19.2 %Sedgwick County19.2Delta County: 19 %Delta County19Logan County: 18.7 %Logan County18.7Denver County: 18.2 %Denver County18.2Costilla County: 18.2 %Costilla County18.2Saguache County: 18.2 %Saguache County18.2Routt County: 17.8 %Routt County17.8Jefferson County: 17.8 %Jefferson County17.8Larimer County: 17.7 %Larimer County17.7La Plata County: 17.1 %La Plata County17.1Yuma County: 27.3 %Yuma County27.3Conejos County: 26.4 %Conejos County26.4Morgan County: 26.3 %Morgan County26.3Prowers County: 25.5 %Prowers County25.5Weld County: 25.4 %Weld County25.4Cheyenne County: 25.3 %Cheyenne County25.3Kiowa County: 25.2 %Kiowa County25.2Phillips County: 25 %Phillips County25Kit Carson County: 24.9 %Kit Carson County24.9Adams County: 23.6 %Adams County23.6Alamosa County: 23.3 %Alamosa County23.3Moffat County: 23.3 %Moffat County23.3Garfield County: 23.2 %Garfield County23.2Douglas County: 22.8 %Douglas County22.8Otero County: 22.8 %Otero County22.8Washington County: 22.6 %Washington County22.6El Paso County: 22.4 %El Paso County22.4Arapahoe County: 22.3 %Arapahoe County22.3Rio Blanco County: 22.2 %Rio Blanco County22.2Baca County: 21.9 %Baca County21.9Elbert County: 21.3 %Elbert County21.3Pueblo County: 21.3 %Pueblo County21.3Lake County: 20.7 %Lake County20.7Montezuma County: 20.5 %Montezuma County20.5Rio Grande County: 20.1 %Rio Grande County20.1Lincoln County: 19.8 %Lincoln County19.8Montrose County: 19.5 %Montrose County19.5Mesa County: 19.5 %Mesa County19.5Eagle County: 19.2 %Eagle County19.2Broomfield County: 19.2 %Broomfield County19.2Sedgwick County: 19.2 %Sedgwick County19.2Delta County: 19 %Delta County19Logan County: 18.7 %Logan County18.7Denver County: 18.2 %Denver County18.2Costilla County: 18.2 %Costilla County18.2Saguache County: 18.2 %Saguache County18.2Routt County: 17.8 %Routt County17.8Jefferson County: 17.8 %Jefferson County17.8Larimer County: 17.7 %Larimer County17.7La Plata County: 17.1 %La Plata County17.1
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2024 (%)Change on 2023
1Yuma County27.3-0.1 pts
2Conejos County26.4-0.1 pts
3Morgan County26.3-0.2 pts
4Prowers County25.5+0.1 pts
5Weld County25.4-0.3 pts
6Cheyenne County25.3+0.3 pts
7Kiowa County25.2+0.9 pts
8Phillips County25+0.2 pts
9Kit Carson County24.90 pts
10Adams County23.6-0.3 pts
11Alamosa County23.3-0.4 pts
12Moffat County23.3-0.3 pts
13Garfield County23.2-0.4 pts
14Douglas County22.8-0.6 pts
15Otero County22.8-0 pts
16Washington County22.6-0.7 pts
17El Paso County22.4-0.3 pts
18Arapahoe County22.3-0.2 pts
19Rio Blanco County22.2-1.2 pts
20Baca County21.9-0.2 pts
21Elbert County21.3-0.4 pts
22Pueblo County21.3-0.3 pts
23Lake County20.7-0.1 pts
24Montezuma County20.5-0.1 pts
25Rio Grande County20.1-0.1 pts
26Lincoln County19.8-0.6 pts
27Montrose County19.5-0.4 pts
28Mesa County19.5-0.5 pts
29Eagle County19.2-0.7 pts
30Broomfield County19.2-0.6 pts
31Sedgwick County19.2-0.3 pts
32Delta County19-0.2 pts
33Logan County18.7-0.3 pts
34Denver County18.20 pts
35Costilla County18.20 pts
35Saguache County18.2-1.3 pts
37Routt County17.8-0.4 pts
38Jefferson County17.8-0.3 pts
39Larimer County17.7-0.4 pts
40La Plata County17.1-0.4 pts
41Jackson County17-1.8 pts
42Archuleta County17-0.2 pts
43San Miguel County16.8-0.7 pts
44Las Animas County16.8-0.3 pts
45Boulder County16.7-0.5 pts
46Dolores County16.2-0.1 pts
47Summit County16+0.1 pts
48Custer County15.8-0.5 pts
49Teller County15.7-0.3 pts
50Gunnison County15.7-0.3 pts
51Pitkin County15.7-0.2 pts
52Bent County15.4-0.6 pts
53Fremont County15.3-0.2 pts
54Grand County15-0.2 pts
55Chaffee County14.9-0.1 pts
56Park County14.8-0.2 pts
57Huerfano County14.2-0.6 pts
58Hinsdale County14.1-1.3 pts
59Gilpin County12.9-0.6 pts
60Ouray County12.4-0.3 pts
61Clear Creek County12-0.8 pts
62San Juan County11.9+0.1 pts
63Crowley County10.9+0.1 pts
64Mineral County10.5+0.3 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, 2024) [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, 2024. 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?period=2024. 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, 2024. 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?period=2024.

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, 2024 [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?period=2024 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_colorado_by_2024,
  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, 2024}},
  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?period=2024. 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, 2024
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?period=2024
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-under-18/colorado-counties?period=2024.
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 27.3% in 2024, according to the U.S. Census Bureau.

Which county has the lowest population under 18?

Mineral County, with 10.5% in 2024.

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