Counties in New Mexico by population under 18

Lea County had the highest population under 18 of 33 counties in 2020, at 29.4%. Catron County had the lowest, at 10.6%. The median was 21.7% and the figure for New Mexico was 22.6%. Source: the U.S. Census Bureau.

Highest29.4Lea County

Lowest10.6Catron County

Median21.733 counties

New Mexico22.6History

Map of counties, 2020

Under 17
17 to 19
19 to 22
22 to 23
23 to 26
26 and over

%, 2020. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2020

%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2020 (%)	Change on 2019
1	Lea County	29.4	+0.4 pts
2	McKinley County	27.7	-0.3 pts
3	Curry County	27.2	+0.4 pts
4	Chaves County	26.4	0 pts
5	San Juan County	26.4	-0.3 pts
6	Eddy County	26.2	-0 pts
7	Luna County	25.3	+0.4 pts
8	Roosevelt County	24.7	-0.1 pts
9	Doña Ana County	24	-0.2 pts
10	Valencia County	23.6	-0.1 pts
11	Cibola County	23.5	-0.2 pts
12	Sandoval County	23.3	-0.4 pts
13	Otero County	23.2	+0.1 pts
14	Los Alamos County	22.3	-0.4 pts
15	Hidalgo County	22.2	-0.5 pts
16	Quay County	21.8	-0.4 pts
17	Rio Arriba County	21.7	-0 pts
18	Socorro County	21.6	+0.1 pts
19	Bernalillo County	21.2	-0.2 pts
20	Torrance County	20.9	+0.4 pts
21	Union County	20	-0 pts
22	De Baca County	19.6	-1.2 pts
23	San Miguel County	19.1	-0.4 pts
24	Grant County	19	-0.2 pts
25	Guadalupe County	18.5	-1.5 pts
26	Colfax County	18	-0.3 pts
27	Lincoln County	17.6	-0.1 pts
28	Taos County	17.4	-0.4 pts
29	Santa Fe County	17.2	-0.5 pts
30	Mora County	17	-0.7 pts
31	Sierra County	15.6	-0 pts
32	Harding County	13	-0.8 pts
33	Catron County	10.6	+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 New Mexico by population under 18, 2020) [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 New Mexico by population under 18, 2020. 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/new-mexico-counties?period=2020. 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 New Mexico by population under 18, 2020. 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/new-mexico-counties?period=2020.

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 New Mexico by population under 18, 2020 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/population-under-18/new-mexico-counties?period=2020 (Accessed: 12 October 2026).

BibTeX

@misc{census_counties_in_new_mexico_2020,
  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 New Mexico by population under 18, 2020}},
  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/new-mexico-counties?period=2020. 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 New Mexico by population under 18, 2020
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/new-mexico-counties?period=2020
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-under-18/new-mexico-counties?period=2020.
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?

Lea County, with 29.4% in 2020, according to the U.S. Census Bureau.

Which county has the lowest population under 18?

Catron County, with 10.6% in 2020.

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.