% Below 18 Years of Age*

About

Percentage of population below 18 years of age. The 2024 Annual Data Release used data from 2022 for this measure.

Children have health needs and risks unique to their developmental phase. Exposures during developmental periods can result in long-term health impacts. Community conditions, including social, political, economic and physical environment factors, can impact the current and future health of children and communities. Safe, stable, nurturing relationships and environments are key,1 yet resources to foster good health are not available to everyone. The accumulation of power in the hands of a few has created a path of advantage for some and disadvantage for others. Society’s written and unwritten rules, such as policies, laws, priorities and traditions, influence our ability and willingness to act together in ways that could benefit health and well-being for everyone. 

Data and methods

Data Source

Census Population Estimates Program

The Census Bureau’s Population Estimates Program (PEP) uses data on births, deaths, and migration to estimate population changes occurring since the most recent decennial census and produce a vintage, or annual time series of estimates. Each vintage includes the current data year and revised estimates for any earlier years since the last decennial census. 

Because each vintage of estimates includes all years since the most recent decennial census, the latest vintage supersedes all other estimates produced since the previous decennial census. 

See the Population Estimates Program methodology for statements and release notes for each vintage of population estimates. See the Limitations section for specific details pertaining to the current vintage year population estimates.

Website to download data
For more detailed methodological information

Key Measure Methods

% Below 18 Years of Age is a percentage

% Below 18 Years of Age is the percentage of the population below 18 years of age.

Numerator

The numerator is the county population below 18 years of age.

Denominator

The denominator is the total county resident population.

The method for calculating % Below 18 Years of Age has changed

Due to the impacts of the COVID-19 pandemic and changes to confidentiality protections for the 2020 decennial census, the 2020 census could not be used as the base population, or starting point, to estimate changes in the population. For the Vintage 2022 population estimates, the census created a Blended Base using 2020 census data, 2020 Demographic Analysis Estimates, and Vintage 2020 Population Estimates for April 1, 2020. At the national level, the age and sex characteristics for the Blended Base come from the 2020 Demographic Analysis Estimates. At the county level, age and sex estimates for the base population come from a blend of these three datasets.  

There were also methodological changes to the estimates of births, deaths, and migration, partially to adjust for the impacts of the COVID-19 pandemic. 2 

Caution should be used when comparing these estimates across years

The population estimates vintage data used for this measure include estimates for all years since the most recent decennial census and therefore supersede all previously produced estimates for those dates. For this reason, population and demographic estimates are best compared within the same vintage series. CHR&R data draw from the most recent vintage available each year and therefore include multiple vintage series over time. 

Measure limitations

The data for this measure come from the Population Estimates Program, which uses survey data from the decennial census and American Community Survey and administrative records such as birth and death certificates. The measure is subject to the limitations of these data sources. 

Finding More Data

Disaggregation means breaking data down into smaller, meaningful subgroups. Disaggregated data are often broken down by characteristics of people or where they live. Disaggregated data can reveal inequalities that are otherwise hidden. These data can be disaggregated by:

  • Age
  • Gender
  • Race
  • Subcounty Area

Population estimates are available by age, sex, race, and subcounty from the U.S. Census Bureau.

References

  1. Jones NL, Gilman SE, Cheng TL, et al. Life course approaches to the causes of health disparities. American Journal of Public Health. 2019;109(Suppl 1):48-55.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6356123/  
  2. U.S. Census Bureau Population Estimates Program. Methodology for the United States population estimates: Vintage 2022. 2022. https://www2.census.gov/programs-surveys/popest/technical-documentation/methodology/2020-2022/methods-statement-v2022.pdf