Age 2023

Meta Data Name: Age Variables  
Date Added: May 5, 2025  
Authors: Mahjabin Kabir Adrita  
Date Last Modified: May 5, 2025  
Last Modified By: Mahjabin Kabir Adrita

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### Theme:  
Demographics – Age Composition

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### Data Location:  
You can find the variables described in this document in the CSV files here.

CSV files are organized by year and spatial scale. For example, county-level variables from 2020 will be found in `C_2020.csv`.  
**Note:** Every variable can be found in the **Latest** files.

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### Data Source(s) Description:  
Variables were obtained from the *American Community Survey (ACS)* 5-Year Estimates, 2019–2023 (tables B01001 and DP05), at the Tract, County, and ZIP Code Tabulation Area (ZCTA) levels.

The ACS is a yearly survey administered by the U.S. Census Bureau that collects detailed demographic, social, economic, and housing information.

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### Description of Data Source Tables:  
**Table B01001:** Sex by Age  
**Table DP05:** ACS Demographic and Housing Estimates  

These tables provide population counts by age and sex. From these, percentages for population segments such as “under 5 years,” “under 18 years,” “over 62 years,” etc., are calculated by dividing each segment count by the total population.

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### Description of Data Processing:  
Percentage values were computed for various age groups by dividing the population within an age category by the total population and multiplying by 100. All variables are reported as percentages (0–100), rounded to two decimal places. Values may slightly differ from official published statistics due to rounding or methodological differences.

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### Key Variable and Definitions:

| Variable                | Variable ID in .csv | Description                                               | Years Available | Spatial Scale         |
|-------------------------|---------------------|-----------------------------------------------------------|------------------|------------------------|
| Percent over age 16     | Ovr16P              | Percent of population over age 16                         | 2023, 2020       | Tract, ZCTA, County    |
| Percent over age 18     | Ovr18P              | Percent of population over age 18                         | 2023, 2020       | Tract, ZCTA, County    |
| Percent over age 21     | Ovr21P              | Percent of population over age 21                         | 2023, 2020       | Tract, ZCTA, County    |
| Percent over age 62     | Ovr62P              | Percent of population over age 62                         | 2023, 2020       | Tract, ZCTA, County    |
| Percent under age 18    | Und18P              | Percent of population under age 18                        | 2023, 2020       | Tract, ZCTA, County    |
| Percent under age 5     | Und5P               | Percent of population under age 5                         | 2023, 2020       | Tract, ZCTA, County    |

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### Data Limitations:  
- The ACS does not include data for U.S. territories (except Puerto Rico).  
- ZCTA-level data is only available for the most recent ACS release (“Latest”).  
- Small-area estimates (e.g., census tracts) may have higher margins of error.  

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### Comments/Notes:  
For definitions and detailed methodology of ACS variables, consult the [ACS 2023 Subject Definitions](https://www.census.gov/programs-surveys/acs/technical-documentation/code-lists.html).  
When aggregating or comparing across geographies, consider differences in population size and data reliability.