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 2023, at 27.5%. Mineral County had the lowest, at 10.2%. The median was 19.3% and the figure for Colorado was 20.8%. Source: the U.S. Census Bureau.

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Highest27.5Yuma County
Lowest10.2Mineral County
Median19.364 counties
Colorado20.8History

Map of counties, 2023

Adams County: 23.9 %Alamosa County: 23.7 %Arapahoe County: 22.5 %Archuleta County: 17.2 %Baca County: 22.1 %Bent County: 16.1 %Boulder County: 17.2 %Broomfield County: 19.8 %Chaffee County: 15.1 %Cheyenne County: 25 %Clear Creek County: 12.8 %Conejos County: 26.5 %Costilla County: 18.2 %Crowley County: 10.8 %Custer County: 16.2 %Delta County: 19.2 %Denver County: 18.2 %Dolores County: 16.3 %Douglas County: 23.5 %Eagle County: 20 %Elbert County: 21.7 %El Paso County: 22.7 %Fremont County: 15.4 %Garfield County: 23.5 %Gilpin County: 13.5 %Grand County: 15.2 %Gunnison County: 16 %Hinsdale County: 15.4 %Huerfano County: 14.8 %Jackson County: 18.8 %Jefferson County: 18.1 %Kiowa County: 24.2 %Kit Carson County: 24.9 %Lake County: 20.8 %La Plata County: 17.4 %Larimer County: 18.1 %Las Animas County: 17.1 %Lincoln County: 20.4 %Logan County: 18.9 %Mesa County: 19.9 %Mineral County: 10.2 %Moffat County: 23.6 %Montezuma County: 20.6 %Montrose County: 20 %Morgan County: 26.5 %Otero County: 22.8 %Ouray County: 12.7 %Park County: 15 %Phillips County: 24.8 %Pitkin County: 15.9 %Prowers County: 25.4 %Pueblo County: 21.6 %Rio Blanco County: 23.4 %Rio Grande County: 20.2 %Routt County: 18.2 %Saguache County: 19.5 %San Juan County: 11.8 %San Miguel County: 17.6 %Sedgwick County: 19.5 %Summit County: 15.9 %Teller County: 16.1 %Washington County: 23.3 %Weld County: 25.7 %Yuma County: 27.5 %
  • Under 15
  • 15 to 17
  • 17 to 19
  • 19 to 22
  • 22 to 24
  • 24 and over
%, 2023. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

Top 40 counties, 2023

Yuma County: 27.5 %Yuma County27.5Conejos County: 26.5 %Conejos County26.5Morgan County: 26.5 %Morgan County26.5Weld County: 25.7 %Weld County25.7Prowers County: 25.4 %Prowers County25.4Cheyenne County: 25 %Cheyenne County25Kit Carson County: 24.9 %Kit Carson County24.9Phillips County: 24.8 %Phillips County24.8Kiowa County: 24.2 %Kiowa County24.2Adams County: 23.9 %Adams County23.9Alamosa County: 23.7 %Alamosa County23.7Moffat County: 23.6 %Moffat County23.6Garfield County: 23.5 %Garfield County23.5Douglas County: 23.5 %Douglas County23.5Rio Blanco County: 23.4 %Rio Blanco County23.4Washington County: 23.3 %Washington County23.3Otero County: 22.8 %Otero County22.8El Paso County: 22.7 %El Paso County22.7Arapahoe County: 22.5 %Arapahoe County22.5Baca County: 22.1 %Baca County22.1Elbert County: 21.7 %Elbert County21.7Pueblo County: 21.6 %Pueblo County21.6Lake County: 20.8 %Lake County20.8Montezuma County: 20.6 %Montezuma County20.6Lincoln County: 20.4 %Lincoln County20.4Rio Grande County: 20.2 %Rio Grande County20.2Eagle County: 20 %Eagle County20Montrose County: 20 %Montrose County20Mesa County: 19.9 %Mesa County19.9Broomfield County: 19.8 %Broomfield County19.8Saguache County: 19.5 %Saguache County19.5Sedgwick County: 19.5 %Sedgwick County19.5Delta County: 19.2 %Delta County19.2Logan County: 18.9 %Logan County18.9Jackson County: 18.8 %Jackson County18.8Routt County: 18.2 %Routt County18.2Denver County: 18.2 %Denver County18.2Costilla County: 18.2 %Costilla County18.2Larimer County: 18.1 %Larimer County18.1Jefferson County: 18.1 %Jefferson County18.1Yuma County: 27.5 %Yuma County27.5Conejos County: 26.5 %Conejos County26.5Morgan County: 26.5 %Morgan County26.5Weld County: 25.7 %Weld County25.7Prowers County: 25.4 %Prowers County25.4Cheyenne County: 25 %Cheyenne County25Kit Carson County: 24.9 %Kit Carson County24.9Phillips County: 24.8 %Phillips County24.8Kiowa County: 24.2 %Kiowa County24.2Adams County: 23.9 %Adams County23.9Alamosa County: 23.7 %Alamosa County23.7Moffat County: 23.6 %Moffat County23.6Garfield County: 23.5 %Garfield County23.5Douglas County: 23.5 %Douglas County23.5Rio Blanco County: 23.4 %Rio Blanco County23.4Washington County: 23.3 %Washington County23.3Otero County: 22.8 %Otero County22.8El Paso County: 22.7 %El Paso County22.7Arapahoe County: 22.5 %Arapahoe County22.5Baca County: 22.1 %Baca County22.1Elbert County: 21.7 %Elbert County21.7Pueblo County: 21.6 %Pueblo County21.6Lake County: 20.8 %Lake County20.8Montezuma County: 20.6 %Montezuma County20.6Lincoln County: 20.4 %Lincoln County20.4Rio Grande County: 20.2 %Rio Grande County20.2Eagle County: 20 %Eagle County20Montrose County: 20 %Montrose County20Mesa County: 19.9 %Mesa County19.9Broomfield County: 19.8 %Broomfield County19.8Saguache County: 19.5 %Saguache County19.5Sedgwick County: 19.5 %Sedgwick County19.5Delta County: 19.2 %Delta County19.2Logan County: 18.9 %Logan County18.9Jackson County: 18.8 %Jackson County18.8Routt County: 18.2 %Routt County18.2Denver County: 18.2 %Denver County18.2Costilla County: 18.2 %Costilla County18.2Larimer County: 18.1 %Larimer County18.1Jefferson County: 18.1 %Jefferson County18.1
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2023 (%)Change on 2022
1Yuma County27.5+0.1 pts
2Conejos County26.5-0.2 pts
3Morgan County26.50 pts
4Weld County25.7-0.3 pts
5Prowers County25.4-0.1 pts
6Cheyenne County25-0.5 pts
7Kit Carson County24.9-0.1 pts
8Phillips County24.8+0.4 pts
9Kiowa County24.2+0.4 pts
10Adams County23.9-0.5 pts
11Alamosa County23.7-0.4 pts
12Moffat County23.6-0.3 pts
13Garfield County23.5-0.6 pts
14Douglas County23.5-0.5 pts
15Rio Blanco County23.4-0.6 pts
16Washington County23.3+0.1 pts
17Otero County22.8-0.4 pts
18El Paso County22.7-0.3 pts
19Arapahoe County22.5-0.3 pts
20Baca County22.1+0.4 pts
21Elbert County21.7+0.1 pts
22Pueblo County21.6-0.3 pts
23Lake County20.8-0.2 pts
24Montezuma County20.6-0.1 pts
25Lincoln County20.4-0.1 pts
26Rio Grande County20.2-0.8 pts
27Eagle County20-0.7 pts
28Montrose County20-0.3 pts
29Mesa County19.9-0.4 pts
30Broomfield County19.8-0.5 pts
31Saguache County19.5+0.3 pts
32Sedgwick County19.5+0.3 pts
33Delta County19.2-0.3 pts
34Logan County18.9-0.1 pts
35Jackson County18.8+1.2 pts
36Routt County18.2-0.2 pts
37Denver County18.2-0.2 pts
38Costilla County18.2-0 pts
39Larimer County18.1-0.4 pts
40Jefferson County18.1-0.4 pts
41San Miguel County17.6-0.6 pts
42La Plata County17.4-0.3 pts
43Archuleta County17.2-0.2 pts
44Boulder County17.2-0.6 pts
45Las Animas County17.1-0.5 pts
46Dolores County16.3-0.1 pts
47Custer County16.2+0.4 pts
48Teller County16.1-0.5 pts
49Bent County16.1-0.5 pts
50Gunnison County16-0.3 pts
51Summit County15.9-0.2 pts
52Pitkin County15.9-0.3 pts
53Fremont County15.4-0.2 pts
54Hinsdale County15.4-0.3 pts
55Grand County15.2-0.2 pts
56Chaffee County15.1-0.1 pts
57Park County15-0.2 pts
58Huerfano County14.8-0.6 pts
59Gilpin County13.5-0.9 pts
60Clear Creek County12.8-0.6 pts
61Ouray County12.7-1 pts
62San Juan County11.8-0.3 pts
63Crowley County10.8-0.5 pts
64Mineral County10.2+0.7 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, 2023) [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, 2023. 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=2023. 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, 2023. 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=2023.

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, 2023 [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=2023 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_colorado_by_2023,
  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, 2023}},
  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=2023. 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, 2023
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=2023
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-under-18/colorado-counties?period=2023.
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 27.5% in 2023, according to the U.S. Census Bureau.

Which county has the lowest population under 18?

Mineral County, with 10.2% in 2023.

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