Illinois Population by Age

The median age in Illinois is 38.5, as per 2021 ACS 5-Year Estimates. Of the total population, 18.51% were under the age of 15, 20.00% aged 15 to 29, 45.79% aged 30 to 64, 13.71% aged 65 to 84, and 1.99% were 85 years of age and older.
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Updated Sep 17, 2023

Illinois population age distribution

A complete breakdown of Illinois's age demographics from 0 to 85 years, distributed across 18 age groups is listed in the table below.

Age Group Population % of Total Population
Under 5 years 745,681 5.82%
5 to 9 years 781,334 6.09%
10 to 14 years 846,355 6.6%
15 to 19 years 850,104 6.63%
20 to 24 years 833,461 6.5%
25 to 29 years 880,487 6.87%
30 to 34 years 871,055 6.79%
35 to 39 years 863,527 6.73%
40 to 44 years 813,194 6.34%
45 to 49 years 813,111 6.34%
50 to 54 years 827,372 6.45%
55 to 59 years 869,497 6.78%
60 to 64 years 813,900 6.35%
65 to 69 years 671,496 5.24%
70 to 74 years 518,791 4.05%
75 to 79 years 339,908 2.65%
80 to 84 years 227,343 1.77%
85 years and over 255,197 1.99%
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Illinois population by age group

Key stats
4,056,935
Population under 25 years
3,428,263
Population aged 25-44
3,323,880
Population aged 45-64
2,012,735
Population aged 65+

Sources: U.S. Census Bureau, American Community Survey (ACS) 2021

The graph shows Illinois's population by age group, with age group on x-axis and the respective age group's percent of the total population on y-axis
Illinois population by age group. The largest age group was 25-29 years with a poulation of 880,487 (6.87% of the total population). Source: U.S. Census Bureau American Community Survey (ACS) 2017-2021 5-Year Estimates.

The largest age group in Illinois was for the group of age 25-29 years with a population of 880,487 (6.87%), according to the 2021 American Community Survey.

At the same time, the smallest age group in Illinois was the 80-84 years with a population of 227,343 (1.77%).

Illinois population by age cohort

To better understand the age distribution of Illinois's population, we divided it into the following 3 cohorts:

  • Children : Under the age of 18 years
  • Adults (working population): Between the age of 18 and 64 years
  • Seniors: 65 years and above
The pie chart shows Illinois's population divided into segments, with each segment representing an age cohort. The area of each segment is in the same proportion of a circle as the population of the cohort is of the total population.
Illinois population by age cohorts (Children: Under 18 years; Working population: 18-64 years; Senior population: 65 years or more). The largest age group was 18 - 64 years with a poulation of 7,921,727 (61.78% of the total population). Source: U.S. Census Bureau American Community Survey (ACS) 2017-2021 5-Year Estimates.

Here's the population for each of the three cohorts.

Age Group Population % of Total Population
Under 18 years 2,887,351 22.52%
18 to 64 years 7,921,727 61.78%
85 years and over 2,012,735 15.7%
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Key stats for each age cohort as per our analysis of U.S. Census Bureau American Community Survey:

  • Illinois's population under 18 was 22.52%, compared to the 22.51% nationwide.
  • Illinois's working population (between 18 and 64) was 61.78%, compared to 61.45% nationwide.
  • Illinois's elderly or the senior population (over 65 age) was 15.70% as compared to 16.04% nationwide.

Illinois population pyramid

Population pyramid for Illinois is charted below using the estimates from U.S. Census Bureau's American Community Survey 5-Year estimates. A wide base suggests population increase, narrow base indicates declining birth rates.

Key stats from our analysis of the Illinois's population pyramid:

  • Youth dependency ratio, which is the number of children aged 0-14 per 100 persons aged 15-64, for Illinois, is 28.1.
  • Old-age dependency ratio, which is the number of persons aged 65 or over per 100 persons aged 15-64, for Illinois, is 23.9.
  • Total dependency ratio for Illinois is 52.0.
  • Potential support ratio, which is the number of youth (working age population) per elderly, for Illinois is 4.2.
The graph shows Illinois's population across different age group and gender, with population on x-axis and population y-axis. The male population is plotted on the left in blue color whereas the female population is plotted on the right in pink color.
Illinois population pyramid i.e. Illinois population distrubution across age and gender. Source: U.S. Census Bureau American Community Survey (ACS) 2017-2021 5-Year Estimates.

Here's the Illinois's male and female population across different age groups:

Age Group Population(Male) Population(Female) Total Population
Under 5 years 381,213 364,468 745,681
5 to 9 years 397,940 383,394 781,334
10 to 14 years 433,292 413,063 846,355
15 to 19 years 434,936 415,168 850,104
20 to 24 years 422,693 410,768 833,461
25 to 29 years 443,153 437,334 880,487
30 to 34 years 439,475 431,580 871,055
35 to 39 years 434,478 429,049 863,527
40 to 44 years 409,290 403,904 813,194
45 to 49 years 406,583 406,528 813,111
50 to 54 years 412,702 414,670 827,372
55 to 59 years 431,013 438,484 869,497
60 to 64 years 395,189 418,711 813,900
65 to 69 years 318,962 352,534 671,496
70 to 74 years 240,656 278,135 518,791
75 to 79 years 149,160 190,748 339,908
80 to 84 years 94,438 132,905 227,343
85 years and over 87,003 168,194 255,197
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Things to know

What is the population of Illinois under 18?

Illinois's population under the age of 18 is 2,887,351, as per the latest U.S. Census Bureau's American Community Survey estimates. This population is 22.52% of the total resident population of Illinois.

What is the aging population in Illinois?

Illinois's population aged 65 years and above was 2,012,735. As per the U.S. Census Bureau's American Community Survey, this population is 15.70% of the entire population.

References

Datasets

Explore datasets by year of publication.
2023
Illinois Age Group Population Dataset: A complete breakdown of Illinois age demographics from 0 to 85 years, distributed across 18 age groups
Last updated September 16, 2023
ACS
Free
Neilsberg
CSV, JSON
2017-2021
CC BY 4.0
About this dataset

Context

The dataset tabulates the Illinois population distribution across 18 age groups. It lists the population in each age group along with the percentage population relative of the total population for Illinois. The dataset can be utilized to understand the population distribution of Illinois by age. For example, using this dataset, we can identify the largest age group in Illinois.

Key observations

The largest age group in Illinois was for the group of age 25-29 years with a population of 880,487 (6.87%), according to the 2021 American Community Survey. At the same time, the smallest age group in Illinois was the 80-84 years with a population of 227,343 (1.77%). Source: U.S. Census Bureau American Community Survey (ACS) 2017-2021 5-Year Estimates.

Illinois population by age group

Content

When available, the data consists of estimates from the U.S. Census Bureau American Community Survey (ACS) 2017-2021 5-Year Estimates.

Age groups:

  • Under 5 years
  • 5 to 9 years
  • 10 to 14 years
  • 15 to 19 years
  • 20 to 24 years
  • 25 to 29 years
  • 30 to 34 years
  • 35 to 39 years
  • 40 to 44 years
  • 45 to 49 years
  • 50 to 54 years
  • 55 to 59 years
  • 60 to 64 years
  • 65 to 69 years
  • 70 to 74 years
  • 75 to 79 years
  • 80 to 84 years
  • 85 years and over

Variables / Data Columns

  • Age Group: This column displays the age group in consideration
  • Population: The population for the specific age group in the Illinois is shown in this column.
  • % of Total Population: This column displays the population of each age group as a proportion of Illinois total population. Please note that the sum of all percentages may not equal one due to rounding of values.

Good to know

Margin of Error

Data in the dataset are based on the estimates and are subject to sampling variability and thus a margin of error. Neilsberg Research recommends using caution when presening these estimates in your research.

Custom data

If you do need custom data for any of your research project, report or presentation, you can contact our research staff at research@neilsberg.com for a feasibility of a custom tabulation on a fee-for-service basis.

Inspiration

Neilsberg Research Team curates, analyze and publishes demographics and economic data from a variety of public and proprietary sources, each of which often includes multiple surveys and programs. The large majority of Neilsberg Research aggregated datasets and insights is made available for free download at https://www.neilsberg.com/research/.

Recommended for further research

This dataset is a part of the main dataset for Illinois Population by Age. You can refer the same here

Illinois Age Cohorts Dataset: Children, Working Adults, and Seniors in Illinois - Population and Percentage Analysis
Last updated September 16, 2023
ACS
Free
Neilsberg
CSV, JSON
2017-2021
CC BY 4.0
About this dataset

Context

The dataset tabulates the Illinois population by age cohorts (Children: Under 18 years; Working population: 18-64 years; Senior population: 65 years or more). It lists the population in each age cohort group along with its percentage relative to the total population of Illinois. The dataset can be utilized to understand the population distribution across children, working population and senior population for dependency ratio, housing requirements, ageing, migration patterns etc.

Key observations

The largest age group was $b3_v1 with a poulation of $b3_v2 ($b3_v3 of the total population). Source: U.S. Census Bureau American Community Survey (ACS) 2017-2021 5-Year Estimates.

Illinois population by age cohort

Content

When available, the data consists of estimates from the U.S. Census Bureau American Community Survey (ACS) 2017-2021 5-Year Estimates.

Age cohorts:

  • Under 18 years
  • 18 to 64 years
  • 65 years and over

Variables / Data Columns

  • Age Group: This column displays the age cohort for the Illinois population analysis. Total expected values are 3 groups ( Children, Working Population and Senior Population).
  • Population: The population for the age cohort in Illinois is shown in the following column.
  • Percent of Total Population: The population as a percent of total population of the Illinois is shown in the following column.

Good to know

Margin of Error

Data in the dataset are based on the estimates and are subject to sampling variability and thus a margin of error. Neilsberg Research recommends using caution when presening these estimates in your research.

Custom data

If you do need custom data for any of your research project, report or presentation, you can contact our research staff at research@neilsberg.com for a feasibility of a custom tabulation on a fee-for-service basis.

Inspiration

Neilsberg Research Team curates, analyze and publishes demographics and economic data from a variety of public and proprietary sources, each of which often includes multiple surveys and programs. The large majority of Neilsberg Research aggregated datasets and insights is made available for free download at https://www.neilsberg.com/research/.

Recommended for further research

This dataset is a part of the main dataset for Illinois Population by Age. You can refer the same here

Illinois Population Pyramid Dataset: Age Groups, Male and Female Population, and Total Population for Demographics Analysis
Last updated September 16, 2023
ACS
Free
Neilsberg
CSV, JSON
2017-2021
CC BY 4.0
About this dataset

Context

The dataset tabulates the data for the Illinois population pyramid, which represents the Illinois population distribution across age and gender, using estimates from the U.S. Census Bureau American Community Survey 5-Year estimates. It lists the male and female population for each age group, along with the total population for those age groups. Higher numbers at the bottom of the table suggest population growth, whereas higher numbers at the top indicate declining birth rates. Furthermore, the dataset can be utilized to understand the youth dependency ratio, old-age dependency ratio, total dependency ratio, and potential support ratio.

Key observations

  • Youth dependency ratio, which is the number of children aged 0-14 per 100 persons aged 15-64, for Illinois, is 28.1.
  • Old-age dependency ratio, which is the number of persons aged 65 or over per 100 persons aged 15-64, for Illinois, is 23.9.
  • Total dependency ratio for Illinois is 52.0.
  • Potential support ratio, which is the number of youth (working age population) per elderly, for Illinois is 4.2.

Illinois population pyramid

Content

When available, the data consists of estimates from the U.S. Census Bureau American Community Survey (ACS) 2017-2021 5-Year Estimates.

Age groups:

  • Under 5 years
  • 5 to 9 years
  • 10 to 14 years
  • 15 to 19 years
  • 20 to 24 years
  • 25 to 29 years
  • 30 to 34 years
  • 35 to 39 years
  • 40 to 44 years
  • 45 to 49 years
  • 50 to 54 years
  • 55 to 59 years
  • 60 to 64 years
  • 65 to 69 years
  • 70 to 74 years
  • 75 to 79 years
  • 80 to 84 years
  • 85 years and over

Variables / Data Columns

  • Age Group: This column displays the age group for the Illinois population analysis. Total expected values are 18 and are define above in the age groups section.
  • Population (Male): The male population in the Illinois for the selected age group is shown in the following column.
  • Population (Female): The female population in the Illinois for the selected age group is shown in the following column.
  • Total Population: The total population of the Illinois for the selected age group is shown in the following column.

Good to know

Margin of Error

Data in the dataset are based on the estimates and are subject to sampling variability and thus a margin of error. Neilsberg Research recommends using caution when presening these estimates in your research.

Custom data

If you do need custom data for any of your research project, report or presentation, you can contact our research staff at research@neilsberg.com for a feasibility of a custom tabulation on a fee-for-service basis.

Inspiration

Neilsberg Research Team curates, analyze and publishes demographics and economic data from a variety of public and proprietary sources, each of which often includes multiple surveys and programs. The large majority of Neilsberg Research aggregated datasets and insights is made available for free download at https://www.neilsberg.com/research/.

Recommended for further research

This dataset is a part of the main dataset for Illinois Population by Age. You can refer the same here

If you're looking for datasets from another year, please feel free to contact us at research@neilsberg.com and we'll be happy to assist you further.

About the author

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Neilsberg Research
Neilsberg Research team are data scientists with expertise in processing, analysis and visualization of big data helping small businesses make right decisions.

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