ACS 5-year Age And Sex (block Group)

Overview

The ACS 5-Year Age and Sex dataset reports population counts split by sex and 23 age buckets for every Census block group in the United States. This dataset enables researchers to build neighborhood-level population pyramids, compute derived measures like median age, dependency ratio, child share, working-age share, senior share, and sex ratio, and study demographic shifts over time.

Published annually by the U.S. Census Bureau as part of the ACS 5-year estimates program, which pools five years of survey responses to provide statistically reliable estimates at small geographies.

Data Description

Each row carries the geoid, state/county FIPS, tract, block_group, name, year_end, vintage, total population, male and female totals, and 46 age-bucketed count columns (23 buckets × 2 sexes): under_5, 5_9, 10_14, 15_17, 18_19, age_20, age_21, 22_24, 25_29, 30_34, 35_39, 40_44, 45_49, 50_54, 55_59, 60_61, 62_64, 65_66, 67_69, 70_74, 75_79, 80_84, 85_plus.

Each estimate has a paired margin-of-error column at the 90% confidence level. Cell sums roll up consistently: bucket male + bucket female = bucket total; all buckets sum to male_total / female_total; male_total + female_total = total, modulo Census rounding. Census uses an irregular bucket grid with finer detail around enrollment- and retirement-age transitions.

Coverage

Geographic Coverage: All Census block groups in the 50 U.S. states, the District of Columbia, and Puerto Rico. Approximately 220,000-242,000 block groups per release year depending on Census's BG redraws.

Temporal Coverage: ACS 5-year releases ending 2013 through 2024 (12 release years).

Observation Level: One row per Census block group per ACS 5-year release year per geometry vintage (keyed by geoid + year_end + vintage).

Vintage Information: Two block-group geographic vintages appear across these datasets because the U.S. Census Bureau redrew block-group boundaries after the 2020 Decennial Census. A vintage column distinguishes the two: '2010' for releases ending 2013-2021 (using 2010 Census BG boundaries) and '2020' for releases ending 2022 and later (using 2020 Census BG boundaries). Block-group GEOIDs do not align 1:1 between vintages — the same physical land area can have a different GEOID before and after the 2020 redraw. Cross-vintage joins should use a Census-published block-group relationship file.

Methodology

Pulled from the U.S. Census Bureau's American Community Survey 5-Year Estimates via the public Census Data API.

Each annual release is the average of five years of survey responses. Block-group estimates are computed by Census using its standard survey-weight methodology.

Additional Notes

All Census Bureau data is in the public domain.

This dataset shares the same geographic key (geoid) and temporal columns (year_end, vintage) as the other Census datasets, so they can be joined row-for-row within a vintage.

For trend analyses crossing the 2021→2022 vintage boundary, restrict the cohort to one vintage or apply a Census-published block-group relationship crosswalk.

Licensing and redistribution. U.S. Census Bureau data products are works of the United States Government and are not subject to copyright: "Copyright protection under this title is not available for any work of the United States Government" (17 U.S.C. § 105). Dewey redistributes this processed extract on that public-domain basis. The Census Bureau requests (but does not require) citation, and prohibits using the data to "identify any individual person, household, business or other entity" — a confidentiality obligation that passes through to users of this dataset. This product uses the Census Bureau Data API but is not endorsed or certified by the Census Bureau.