Data / Rankings / Population under 18 / Counties in Illinois

Counties in Illinois by population under 18

Kendall County had the highest population under 18 of 102 counties in 2014, at 30.3%. Brown County had the lowest, at 15.5%. The median was 22.1% and the figure for Illinois was 23.2%. Source: the U.S. Census Bureau.

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Highest30.3Kendall County
Lowest15.5Brown County
Median22.1102 counties
Illinois23.2History

Map of counties, 2014

Adams County: 22.6 %Alexander County: 23.8 %Bond County: 19.3 %Boone County: 26.5 %Brown County: 15.5 %Bureau County: 21.9 %Calhoun County: 21.2 %Carroll County: 18.7 %Cass County: 24.5 %Champaign County: 19.2 %Christian County: 21.1 %Clark County: 22.8 %Clay County: 22.5 %Clinton County: 21.7 %Coles County: 18.7 %Cook County: 22.4 %Crawford County: 20 %Cumberland County: 23.1 %DeKalb County: 22.4 %De Witt County: 21.8 %Douglas County: 25.4 %DuPage County: 23.5 %Edgar County: 21.5 %Edwards County: 23.4 %Effingham County: 23.6 %Fayette County: 21.4 %Ford County: 23.1 %Franklin County: 22.1 %Fulton County: 20.3 %Gallatin County: 20.3 %Greene County: 22.1 %Grundy County: 26 %Hamilton County: 22.6 %Hancock County: 21.3 %Hardin County: 20 %Henderson County: 19.3 %Henry County: 23 %Iroquois County: 22.3 %Jackson County: 18.4 %Jasper County: 22.8 %Jefferson County: 21.8 %Jersey County: 21.8 %Jo Daviess County: 19.6 %Johnson County: 17.4 %Kane County: 27.3 %Kankakee County: 24.2 %Kendall County: 30.3 %Knox County: 20 %Lake County: 25.5 %LaSalle County: 22 %Lawrence County: 19 %Lee County: 20.2 %Livingston County: 22 %Logan County: 19.4 %McDonough County: 17 %McHenry County: 24.9 %McLean County: 22.2 %Macon County: 22.3 %Macoupin County: 21.6 %Madison County: 22.1 %Marion County: 22.7 %Marshall County: 20.2 %Mason County: 20.8 %Massac County: 22.5 %Menard County: 22.8 %Mercer County: 22.2 %Monroe County: 23.2 %Montgomery County: 20.5 %Morgan County: 20.1 %Moultrie County: 24.8 %Ogle County: 23.4 %Peoria County: 23.7 %Perry County: 19.6 %Piatt County: 22.4 %Pike County: 22.1 %Pope County: 17.8 %Pulaski County: 21.9 %Putnam County: 19.8 %Randolph County: 19.7 %Richland County: 22.3 %Rock Island County: 22.4 %St. Clair County: 24.1 %Saline County: 22.2 %Sangamon County: 22.9 %Schuyler County: 19.9 %Scott County: 22.1 %Shelby County: 21.6 %Stark County: 21.6 %Stephenson County: 21.9 %Tazewell County: 23.3 %Union County: 20.6 %Vermilion County: 23.8 %Wabash County: 21.6 %Warren County: 22.3 %Washington County: 21.1 %Wayne County: 22.9 %White County: 21.4 %Whiteside County: 22.7 %Will County: 26.7 %Williamson County: 21.8 %Winnebago County: 23.7 %Woodford County: 25 %
  • Under 20
  • 20 to 21
  • 21 to 22
  • 22 to 23
  • 23 to 24
  • 24 and over
%, 2014. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

Top 40 counties, 2014

Kendall County: 30.3 %Kendall County30.3Kane County: 27.3 %Kane County27.3Will County: 26.7 %Will County26.7Boone County: 26.5 %Boone County26.5Grundy County: 26 %Grundy County26Lake County: 25.5 %Lake County25.5Douglas County: 25.4 %Douglas County25.4Woodford County: 25 %Woodford County25McHenry County: 24.9 %McHenry County24.9Moultrie County: 24.8 %Moultrie County24.8Cass County: 24.5 %Cass County24.5Kankakee County: 24.2 %Kankakee County24.2St. Clair County: 24.1 %St. Clair County24.1Alexander County: 23.8 %Alexander County23.8Vermilion County: 23.8 %Vermilion County23.8Winnebago County: 23.7 %Winnebago County23.7Peoria County: 23.7 %Peoria County23.7Effingham County: 23.6 %Effingham County23.6DuPage County: 23.5 %DuPage County23.5Ogle County: 23.4 %Ogle County23.4Edwards County: 23.4 %Edwards County23.4Tazewell County: 23.3 %Tazewell County23.3Monroe County: 23.2 %Monroe County23.2Ford County: 23.1 %Ford County23.1Cumberland County: 23.1 %Cumberland County23.1Henry County: 23 %Henry County23Wayne County: 22.9 %Wayne County22.9Sangamon County: 22.9 %Sangamon County22.9Clark County: 22.8 %Clark County22.8Jasper County: 22.8 %Jasper County22.8Menard County: 22.8 %Menard County22.8Marion County: 22.7 %Marion County22.7Whiteside County: 22.7 %Whiteside County22.7Adams County: 22.6 %Adams County22.6Hamilton County: 22.6 %Hamilton County22.6Clay County: 22.5 %Clay County22.5Massac County: 22.5 %Massac County22.5Piatt County: 22.4 %Piatt County22.4Cook County: 22.4 %Cook County22.4Rock Island County: 22.4 %Rock Island County22.4Kendall County: 30.3 %Kendall County30.3Kane County: 27.3 %Kane County27.3Will County: 26.7 %Will County26.7Boone County: 26.5 %Boone County26.5Grundy County: 26 %Grundy County26Lake County: 25.5 %Lake County25.5Douglas County: 25.4 %Douglas County25.4Woodford County: 25 %Woodford County25McHenry County: 24.9 %McHenry County24.9Moultrie County: 24.8 %Moultrie County24.8Cass County: 24.5 %Cass County24.5Kankakee County: 24.2 %Kankakee County24.2St. Clair County: 24.1 %St. Clair County24.1Alexander County: 23.8 %Alexander County23.8Vermilion County: 23.8 %Vermilion County23.8Winnebago County: 23.7 %Winnebago County23.7Peoria County: 23.7 %Peoria County23.7Effingham County: 23.6 %Effingham County23.6DuPage County: 23.5 %DuPage County23.5Ogle County: 23.4 %Ogle County23.4Edwards County: 23.4 %Edwards County23.4Tazewell County: 23.3 %Tazewell County23.3Monroe County: 23.2 %Monroe County23.2Ford County: 23.1 %Ford County23.1Cumberland County: 23.1 %Cumberland County23.1Henry County: 23 %Henry County23Wayne County: 22.9 %Wayne County22.9Sangamon County: 22.9 %Sangamon County22.9Clark County: 22.8 %Clark County22.8Jasper County: 22.8 %Jasper County22.8Menard County: 22.8 %Menard County22.8Marion County: 22.7 %Marion County22.7Whiteside County: 22.7 %Whiteside County22.7Adams County: 22.6 %Adams County22.6Hamilton County: 22.6 %Hamilton County22.6Clay County: 22.5 %Clay County22.5Massac County: 22.5 %Massac County22.5Piatt County: 22.4 %Piatt County22.4Cook County: 22.4 %Cook County22.4Rock Island County: 22.4 %Rock Island County22.4
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2014 (%)Change on 2013
1Kendall County30.3-0.1 pts
2Kane County27.3-0.5 pts
3Will County26.7-0.5 pts
4Boone County26.5-0.5 pts
5Grundy County26-0.3 pts
6Lake County25.5-0.3 pts
7Douglas County25.4-0 pts
8Woodford County25-0.2 pts
9McHenry County24.9-0.4 pts
10Moultrie County24.8-0.2 pts
11Cass County24.5-0.4 pts
12Kankakee County24.2-0.2 pts
13St. Clair County24.1-0.2 pts
14Alexander County23.80 pts
14Vermilion County23.8-0.1 pts
16Winnebago County23.7-0.3 pts
17Peoria County23.7-0 pts
18Effingham County23.6-0.3 pts
19DuPage County23.5-0.3 pts
20Ogle County23.4-0.2 pts
21Edwards County23.4+0.2 pts
22Tazewell County23.30 pts
23Monroe County23.2-0.5 pts
24Ford County23.10 pts
25Cumberland County23.1-0.1 pts
26Henry County23-0.3 pts
27Wayne County22.9+0.1 pts
28Sangamon County22.9-0.1 pts
29Clark County22.8-0 pts
30Jasper County22.8+0.2 pts
31Menard County22.80 pts
32Marion County22.7-0 pts
33Whiteside County22.7-0.2 pts
34Adams County22.60 pts
35Hamilton County22.6-0.1 pts
36Clay County22.5-0.2 pts
37Massac County22.50 pts
38Piatt County22.4-0.4 pts
39Cook County22.4-0.3 pts
39Rock Island County22.4-0 pts
41DeKalb County22.40 pts
42Warren County22.3+0.1 pts
43Macon County22.30 pts
44Iroquois County22.3-0.3 pts
45Richland County22.3+0.3 pts
46Mercer County22.2-0.2 pts
46Saline County22.2-0.2 pts
48McLean County22.2-0.1 pts
49Madison County22.1-0 pts
50Greene County22.1-0.2 pts
51Franklin County22.1-0 pts
52Pike County22.1-0.1 pts
53Scott County22.1-0.2 pts
54Livingston County22-0.3 pts
55LaSalle County22-0.2 pts
56Bureau County21.9-0.2 pts
57Pulaski County21.9-0.4 pts
58Stephenson County21.9-0.1 pts
59Williamson County21.8-0.1 pts
60Jersey County21.8-0.3 pts
61De Witt County21.8-0.5 pts
62Jefferson County21.8-0.1 pts
63Clinton County21.7-0.1 pts
64Stark County21.6-0.4 pts
65Macoupin County21.6-0.3 pts
66Shelby County21.6-0.2 pts
67Wabash County21.6-0.2 pts
68Edgar County21.5-0.1 pts
69Fayette County21.4-0.1 pts
70White County21.4-0.1 pts
71Hancock County21.3+0.1 pts
72Calhoun County21.2-0.2 pts
73Washington County21.1-0.1 pts
74Christian County21.1-0.3 pts
75Mason County20.8-0.1 pts
76Union County20.60 pts
77Montgomery County20.5-0.6 pts
78Gallatin County20.3-0.1 pts
79Fulton County20.3-0.2 pts
80Marshall County20.2-0.7 pts
81Lee County20.2-0.2 pts
82Morgan County20.1-0.4 pts
83Crawford County20-0.2 pts
84Knox County20-0 pts
85Hardin County200 pts
86Schuyler County19.9-0.7 pts
87Putnam County19.8+0.1 pts
88Randolph County19.7+0.2 pts
89Jo Daviess County19.6-0.3 pts
90Perry County19.6-0.4 pts
91Logan County19.4-0.1 pts
92Bond County19.3-0.3 pts
93Henderson County19.3-0.3 pts
94Champaign County19.2-0.1 pts
95Lawrence County19-0.2 pts
96Carroll County18.7-0.5 pts
97Coles County18.7+0.1 pts
98Jackson County18.4+0.2 pts
99Pope County17.8+0.1 pts
100Johnson County17.4-0.3 pts
101McDonough County17+0.1 pts
102Brown County15.5+0.2 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 Illinois by population under 18, 2014) [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 Illinois by population under 18, 2014. 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/illinois-counties?period=2014. 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 Illinois by population under 18, 2014. 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/illinois-counties?period=2014.

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 Illinois by population under 18, 2014 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/population-under-18/illinois-counties?period=2014 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_illinois_by_2014,
  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 Illinois by population under 18, 2014}},
  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/illinois-counties?period=2014. 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 Illinois by population under 18, 2014
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/illinois-counties?period=2014
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-under-18/illinois-counties?period=2014.
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 Illinois by population under 18 using official data, and cite the source.
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Questions

Which county has the highest population under 18?

Kendall County, with 30.3% in 2014, according to the U.S. Census Bureau.

Which county has the lowest population under 18?

Brown County, with 15.5% in 2014.

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 Illinois: more rankings