crosswalk_zip_county
ZIP code (ZCTA) to county mapping. One row per ZIP code. For each ZCTA, maps to the county with the largest land-area overlap per the 2020 Census ZCTA-county relationship file. Use to convert ZIP-level data to county grain.
tier aTier A: official Census relationship file.
overview
overview
33,791 rows — one per ZCTA, mapped to the largest-overlap county.
current vintage — 2020
provenance
source & licensing
authority
U.S. Census Bureau
dataset
2020 Census ZCTA-County relationship file
source url
license
Public domain (U.S. Federal Government work)
citation
U.S. Census Bureau, 2020 ZCTA-to-County relationship file.
schema
fields
| name | type | definition |
|---|---|---|
| county_id | string | 5-character FIPS code identifying the county.Joins dim.counties on county_id. |
| state_id | string | 2-character FIPS code identifying the state.Joins dim.states on state_id. |
| zip_codekey | string | 5-digit ZIP Code Tabulation Area (ZCTA) identifier, stored as a zero-padded string. Primary key; each ZCTA maps to the county with the largest land-area overlap per the 2020 Census ZCTA-county relationship file.Part of primary key. Joins dim.crosswalk_zip_county on zip_code. |
relationships
joins
primary key
zip_code
common joins
not provided
usage
how to use this table
method
Selected the county with the largest land-area overlap per ZCTA.
do not use for
Population-weighted ZIP splits (single largest-overlap assignment); non-ZCTA USPS ZIPs.
last updated · Jul 7, 2026