Counties in South Dakota by population under 18, 2025
Mellette County had the highest population under 18 of 66 counties in 2025, at 40.9%. Fall River County had the lowest, at 15.7%. The median was 24.1% and the figure for South Dakota was 23.5%. Source: the U.S. Census Bureau.
Top 40 counties, 2025
Full ranking
| Rank | Counties | 2025 (%) | Change on 2024 |
|---|---|---|---|
| 1 | Mellette County | 40.9 | +2.9 pts |
| 2 | Dewey County | 38.7 | -0.1 pts |
| 3 | Todd County | 36.6 | -1.2 pts |
| 4 | Corson County | 35.6 | 0 pts |
| 5 | Oglala Lakota County | 35.1 | -0.5 pts |
| 6 | Buffalo County | 35 | -1.4 pts |
| 7 | Jackson County | 35 | -0.6 pts |
| 8 | Ziebach County | 32.7 | +0.5 pts |
| 9 | Hamlin County | 32.5 | -0.3 pts |
| 10 | Bennett County | 30.9 | +0.1 pts |
| 11 | Beadle County | 28.5 | +0.3 pts |
| 12 | Roberts County | 28.2 | -0.1 pts |
| 13 | Charles Mix County | 28.2 | -0.2 pts |
| 14 | Clark County | 28.1 | -0.2 pts |
| 15 | Hanson County | 27.9 | -0.5 pts |
| 16 | Lyman County | 27.7 | +0.5 pts |
| 17 | Turner County | 27.4 | +0.3 pts |
| 18 | Faulk County | 26.8 | +1.1 pts |
| 19 | McCook County | 26.7 | -0.2 pts |
| 20 | Moody County | 26.4 | -0.8 pts |
| 21 | Hutchinson County | 25.8 | -0.1 pts |
| 22 | Douglas County | 25.7 | +0.1 pts |
| 23 | Tripp County | 25.7 | -0.1 pts |
| 24 | Marshall County | 25.6 | -0.9 pts |
| 25 | Jerauld County | 25.4 | +0.1 pts |
| 26 | Kingsbury County | 24.8 | +0.3 pts |
| 27 | Sanborn County | 24.7 | -0.2 pts |
| 28 | Harding County | 24.6 | +0.3 pts |
| 29 | Deuel County | 24.5 | -0.2 pts |
| 30 | Minnehaha County | 24.4 | -0.2 pts |
| 31 | Lincoln County | 24.4 | -0.8 pts |
| 32 | Aurora County | 24.2 | -0.4 pts |
| 33 | Jones County | 24.2 | -0.4 pts |
| 34 | Hyde County | 24 | +1.4 pts |
| 35 | Brule County | 23.8 | -0 pts |
| 36 | Haakon County | 23.8 | -0.1 pts |
| 37 | Butte County | 23.6 | -0.4 pts |
| 38 | Walworth County | 23.4 | -0.1 pts |
| 39 | Gregory County | 23.3 | -0.1 pts |
| 40 | Hand County | 23 | 0 pts |
| 41 | Hughes County | 23 | -0.4 pts |
| 42 | Spink County | 22.9 | +0.2 pts |
| 43 | Union County | 22.9 | -0.4 pts |
| 44 | Grant County | 22.8 | -0.1 pts |
| 45 | Stanley County | 22.4 | -0.3 pts |
| 46 | Miner County | 22.3 | +0.2 pts |
| 47 | Brown County | 22.2 | -0.4 pts |
| 48 | Pennington County | 21.9 | -0.3 pts |
| 49 | Codington County | 21.8 | -0.4 pts |
| 50 | Day County | 21.8 | -0 pts |
| 51 | Perkins County | 21.7 | -0.3 pts |
| 52 | Davison County | 21.5 | -0.4 pts |
| 53 | Edmunds County | 21.1 | -0.4 pts |
| 54 | Lake County | 21 | -0.3 pts |
| 55 | Meade County | 20.7 | -0.7 pts |
| 56 | Brookings County | 20.7 | -0 pts |
| 57 | Campbell County | 20.6 | +0.5 pts |
| 58 | Potter County | 20.2 | +0.5 pts |
| 59 | Yankton County | 19.8 | -0.3 pts |
| 60 | Bon Homme County | 19.3 | +0.2 pts |
| 61 | McPherson County | 19.1 | +0.3 pts |
| 62 | Sully County | 16.8 | -1.3 pts |
| 63 | Lawrence County | 16.3 | -0.5 pts |
| 64 | Clay County | 16.2 | -0.3 pts |
| 65 | Custer County | 15.7 | -0.6 pts |
| 66 | Fall River County | 15.7 | +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.Use this data in your AI agent
Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:
Rank Counties in South Dakota by population under 18 using official data, and cite the source.
rank_places {"indicator":"population_0_17_share","level":"province","within":"South Dakota","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=population_0_17_share&level=province&within=South%20Dakota&limit=10Questions
Which county has the highest population under 18?
Mellette County, with 40.9% in 2025, according to the U.S. Census Bureau.
Which county has the lowest population under 18?
Fall River County, with 15.7% 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.