Data / Rankings / Population under 18 / Counties in Colorado

Counties in Colorado by population under 18

Douglas County had the highest population under 18 of 64 counties in 2015, at 28.5%. Crowley County had the lowest, at 11.8%. The median was 20.8% and the figure for Colorado was 23.2%. Source: the U.S. Census Bureau.

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Highest28.5Douglas County
Lowest11.8Crowley County
Median20.864 counties
Colorado23.2History

Map of counties, 2015

Adams County: 27.7 %Alamosa County: 24.3 %Arapahoe County: 24.6 %Archuleta County: 18.5 %Baca County: 20.8 %Bent County: 15.7 %Boulder County: 20.2 %Broomfield County: 24.1 %Chaffee County: 15.5 %Cheyenne County: 25.3 %Clear Creek County: 16.2 %Conejos County: 28.1 %Costilla County: 17.9 %Crowley County: 11.8 %Custer County: 14.9 %Delta County: 20.8 %Denver County: 20.6 %Dolores County: 19.2 %Douglas County: 28.5 %Eagle County: 23.3 %Elbert County: 22.6 %El Paso County: 24.8 %Fremont County: 16.3 %Garfield County: 25.8 %Gilpin County: 17.7 %Grand County: 18 %Gunnison County: 17.8 %Hinsdale County: 18.1 %Huerfano County: 16 %Jackson County: 17.1 %Jefferson County: 20.8 %Kiowa County: 21.7 %Kit Carson County: 22.5 %Lake County: 22.4 %La Plata County: 19.4 %Larimer County: 20.6 %Las Animas County: 18.6 %Lincoln County: 20 %Logan County: 19.2 %Mesa County: 22.2 %Mineral County: 13.8 %Moffat County: 25.4 %Montezuma County: 22.3 %Montrose County: 22.5 %Morgan County: 27 %Otero County: 23.6 %Ouray County: 16.7 %Park County: 16.9 %Phillips County: 23.8 %Pitkin County: 16.6 %Prowers County: 25.5 %Pueblo County: 23.2 %Rio Blanco County: 24.7 %Rio Grande County: 23.9 %Routt County: 19.8 %Saguache County: 22.4 %San Juan County: 14.8 %San Miguel County: 19.9 %Sedgwick County: 21 %Summit County: 16.5 %Teller County: 18.4 %Washington County: 22.8 %Weld County: 27.2 %Yuma County: 26.1 %
  • Under 17
  • 17 to 19
  • 19 to 21
  • 21 to 23
  • 23 to 25
  • 25 and over
%, 2015. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

Top 40 counties, 2015

Douglas County: 28.5 %Douglas County28.5Conejos County: 28.1 %Conejos County28.1Adams County: 27.7 %Adams County27.7Weld County: 27.2 %Weld County27.2Morgan County: 27 %Morgan County27Yuma County: 26.1 %Yuma County26.1Garfield County: 25.8 %Garfield County25.8Prowers County: 25.5 %Prowers County25.5Moffat County: 25.4 %Moffat County25.4Cheyenne County: 25.3 %Cheyenne County25.3El Paso County: 24.8 %El Paso County24.8Rio Blanco County: 24.7 %Rio Blanco County24.7Arapahoe County: 24.6 %Arapahoe County24.6Alamosa County: 24.3 %Alamosa County24.3Broomfield County: 24.1 %Broomfield County24.1Rio Grande County: 23.9 %Rio Grande County23.9Phillips County: 23.8 %Phillips County23.8Otero County: 23.6 %Otero County23.6Eagle County: 23.3 %Eagle County23.3Pueblo County: 23.2 %Pueblo County23.2Washington County: 22.8 %Washington County22.8Elbert County: 22.6 %Elbert County22.6Kit Carson County: 22.5 %Kit Carson County22.5Montrose County: 22.5 %Montrose County22.5Lake County: 22.4 %Lake County22.4Saguache County: 22.4 %Saguache County22.4Montezuma County: 22.3 %Montezuma County22.3Mesa County: 22.2 %Mesa County22.2Kiowa County: 21.7 %Kiowa County21.7Sedgwick County: 21 %Sedgwick County21Jefferson County: 20.8 %Jefferson County20.8Baca County: 20.8 %Baca County20.8Delta County: 20.8 %Delta County20.8Larimer County: 20.6 %Larimer County20.6Denver County: 20.6 %Denver County20.6Boulder County: 20.2 %Boulder County20.2Lincoln County: 20 %Lincoln County20San Miguel County: 19.9 %San Miguel County19.9Routt County: 19.8 %Routt County19.8La Plata County: 19.4 %La Plata County19.4Douglas County: 28.5 %Douglas County28.5Conejos County: 28.1 %Conejos County28.1Adams County: 27.7 %Adams County27.7Weld County: 27.2 %Weld County27.2Morgan County: 27 %Morgan County27Yuma County: 26.1 %Yuma County26.1Garfield County: 25.8 %Garfield County25.8Prowers County: 25.5 %Prowers County25.5Moffat County: 25.4 %Moffat County25.4Cheyenne County: 25.3 %Cheyenne County25.3El Paso County: 24.8 %El Paso County24.8Rio Blanco County: 24.7 %Rio Blanco County24.7Arapahoe County: 24.6 %Arapahoe County24.6Alamosa County: 24.3 %Alamosa County24.3Broomfield County: 24.1 %Broomfield County24.1Rio Grande County: 23.9 %Rio Grande County23.9Phillips County: 23.8 %Phillips County23.8Otero County: 23.6 %Otero County23.6Eagle County: 23.3 %Eagle County23.3Pueblo County: 23.2 %Pueblo County23.2Washington County: 22.8 %Washington County22.8Elbert County: 22.6 %Elbert County22.6Kit Carson County: 22.5 %Kit Carson County22.5Montrose County: 22.5 %Montrose County22.5Lake County: 22.4 %Lake County22.4Saguache County: 22.4 %Saguache County22.4Montezuma County: 22.3 %Montezuma County22.3Mesa County: 22.2 %Mesa County22.2Kiowa County: 21.7 %Kiowa County21.7Sedgwick County: 21 %Sedgwick County21Jefferson County: 20.8 %Jefferson County20.8Baca County: 20.8 %Baca County20.8Delta County: 20.8 %Delta County20.8Larimer County: 20.6 %Larimer County20.6Denver County: 20.6 %Denver County20.6Boulder County: 20.2 %Boulder County20.2Lincoln County: 20 %Lincoln County20San Miguel County: 19.9 %San Miguel County19.9Routt County: 19.8 %Routt County19.8La Plata County: 19.4 %La Plata County19.4
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2015 (%)Change on 2014
1Douglas County28.5-0.4 pts
2Conejos County28.1-0.4 pts
3Adams County27.7-0.2 pts
4Weld County27.2-0.1 pts
5Morgan County27-0 pts
6Yuma County26.1-0.3 pts
7Garfield County25.8-0.3 pts
8Prowers County25.5-0.1 pts
9Moffat County25.4-0.3 pts
10Cheyenne County25.3+0.6 pts
11El Paso County24.8-0.3 pts
12Rio Blanco County24.7-0.5 pts
13Arapahoe County24.6-0.2 pts
14Alamosa County24.3+0.2 pts
15Broomfield County24.1-0.5 pts
16Rio Grande County23.9-0.4 pts
17Phillips County23.8+0.1 pts
18Otero County23.6-0.4 pts
19Eagle County23.3-0.2 pts
20Pueblo County23.2-0.1 pts
21Washington County22.8+0.6 pts
22Elbert County22.6-0.3 pts
23Kit Carson County22.5-0.2 pts
24Montrose County22.5-0.3 pts
25Lake County22.4-0.7 pts
26Saguache County22.4-0.1 pts
27Montezuma County22.3-0.4 pts
28Mesa County22.2-0.2 pts
29Kiowa County21.7+0.2 pts
30Sedgwick County21+0.8 pts
31Jefferson County20.8-0.3 pts
32Baca County20.8-0.3 pts
33Delta County20.8-0.2 pts
34Larimer County20.6-0.1 pts
35Denver County20.6-0.3 pts
36Boulder County20.2-0.3 pts
37Lincoln County20-0.1 pts
38San Miguel County19.9-0.4 pts
39Routt County19.8-0.2 pts
40La Plata County19.4-0.1 pts
41Dolores County19.2+0.4 pts
42Logan County19.2-0.1 pts
43Las Animas County18.60 pts
44Archuleta County18.5+0.1 pts
45Teller County18.4-0.3 pts
46Hinsdale County18.1+0.5 pts
47Grand County18-0.6 pts
48Costilla County17.9-0 pts
49Gunnison County17.8-0.4 pts
50Gilpin County17.7-0.8 pts
51Jackson County17.1-1.3 pts
52Park County16.9-0 pts
53Ouray County16.7-0 pts
54Pitkin County16.6-0.4 pts
55Summit County16.5-0.2 pts
56Fremont County16.3-0.2 pts
57Clear Creek County16.2+0.2 pts
58Huerfano County16+0.4 pts
59Bent County15.7+0.1 pts
60Chaffee County15.5-0.4 pts
61Custer County14.9-0.1 pts
62San Juan County14.8-0.3 pts
63Mineral County13.8+2.7 pts
64Crowley County11.8-0.9 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, 2015) [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, 2015. 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=2015. 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, 2015. 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=2015.

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, 2015 [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=2015 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_colorado_by_2015,
  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, 2015}},
  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=2015. 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, 2015
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=2015
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-under-18/colorado-counties?period=2015.
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?

Douglas County, with 28.5% in 2015, according to the U.S. Census Bureau.

Which county has the lowest population under 18?

Crowley County, with 11.8% in 2015.

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