Census geography / DOCUMENTED CSV
2020 Census ZCTA → County Crosswalk
See where Census ZCTAs cross county lines, with land-area shares and a largest-land-county flag ready to join.
2020 Census geography
01 / KNOW THE FIT
A useful join starts
with a clear meaning.
What you can do with it
Relate a 2020 ZCTA analysis to counties, inspect areas spanning county boundaries, or choose a consistent county label using the largest land overlap.
What one row means
One relationship between a 2020 Census ZCTA and a 2020 county or county equivalent. All overlaps are retained, including water-only relationships.
Unique keyzcta_code + county_fips
How to join it
Join five-character zcta_code values as text. Keep all county relationships when overlap matters. Use is_primary_land_county = 1 only when your analysis calls for one county per ZCTA; this is a land-based convenience flag.
Coverage, with the edges visible
Covers 33,791 ZCTAs and 3,232 counties and equivalents. 10,186 ZCTAs relate to multiple counties. The file retains 7 water-only relationships and excludes 903 source rows with no ZCTA.
Keep in mind
- ZCTAs approximate postal delivery areas for Census statistics. This is not a current USPS ZIP inventory or an address geocoder.
- Uses 2020 county boundaries, including Connecticut’s former counties. The preparation date does not update the geography.
- Land shares are not population, household, or address weights. County shares may sum to less than one because land outside all ZCTAs is excluded.
We flatten Census relationship and state-reference files, preserve leading zeros, add county and state labels, calculate explicit land-area shares, and validate unique pairs and area partitions. Primary-county ties resolve to the lowest county FIPS.
02 / TRY THE SHAPE
Real rows. Before you buy.
These are the first three rows from the delivered CSV, showing 4 of 14 fields. The free download contains the first five rows and all 14 fields; it is a format sample, not a coverage test.
| zcta_code | county_fips | county_name | zcta_land_share |
|---|---|---|---|
| 00601 | 72001 | Adjuntas Municipio | 0.9876161049 |
| 00601 | 72141 | Utuado Municipio | 0.0123838951 |
| 00602 | 72003 | Aguada Municipio | 0.9997892464 |
03 / NO GUESSING
Every field, explained.
The field dictionary from the current download. CSV has no built-in types; these are the intended import types.
| Field | Type | Meaning |
|---|---|---|
zcta_code | string[5] | 2020 Census ZCTA code. Preserve leading zeros; not a current USPS ZIP inventory. |
county_fips | string[5] | 2020 county or county-equivalent GEOID (state FIPS + county FIPS). |
county_name | string | Census 2020 legal/statistical county-area name. |
state_fips | string[2] | First two characters of county_fips. |
state_abbreviation | string[2] | Census state/territory abbreviation. |
state_name | string | Census state/territory name. |
zcta_land_area_m2 | integer | Land area of the entire ZCTA, square meters. |
county_land_area_m2 | integer | Land area of the entire county, square meters. |
intersection_land_area_m2 | integer | Land area shared by this ZCTA and county, square meters. |
intersection_water_area_m2 | integer | Water area shared by this ZCTA and county, square meters. |
zcta_land_share | decimal[10] | Intersection land / ZCTA land, rounded half up to 10 decimal places. Not a population weight. |
county_land_share | decimal[10] | Intersection land / county land, rounded half up to 10 decimal places. County totals can be less than 1 because some county land has no ZCTA. |
county_count | integer | Number of county relationships for this ZCTA, including water-only overlaps. |
is_primary_land_county | integer[0,1] | 1 for largest land overlap in this ZCTA; ties resolved by lowest county_fips. Convenience flag, not an address assignment. |
04 / INSIDE THE DOWNLOAD
Data, with its context.
One ZIP · 1.6 MB · 8 files. No account or subscription required.
ActuallyCleanData_2020_ZCTA_to_County_Crosswalk.csvThe complete prepared dataset · UTF-8 CSVREADME.mdImport guidance, method, attribution, and limitationsdata_dictionary.jsonTypes and definitions for every fieldexamples.sqlWorking joins and checks for Census geographymetadata.jsonSource provenance, production time, counts, and CSV checksumprovenance.jsonRetained source identifiers, URLs and file checksumsrevision.jsonChanges and free-upgrade eligibility for this ACD revisionsource_row_status.csvIncluded/excluded outcome for every source relationship row
05 / DATES THAT MEAN SOMETHING
Sources, versions & changes.
Source versions identify the inputs. Our processing revision describes how we prepare them. Either kind of change creates a new ACD release; the package date records when it was built.
Current source versions
- ZCTA and county boundaries
- 2020 Census
- Package prepared (UTC)
Source: U.S. Census Bureau. Shares, primary flags and packaging calculated by Actually Clean Data; no Census endorsement.
RELEASE HISTORY
Oct 13, 2026 · current package (UTC)
Rebuilt from retained sources through versioned staging and processing. The delivered CSV is unchanged; the package adds source/processing identities and an explicit revision record. This revision is free to existing purchasers.
October 12, 2026: first ACD release of this 2020 geography. The new processing revision retains identical relationships and calculated shares.
Processing corrections and improvements for your purchased source edition are free. Genuinely new source editions may be sold separately. See the update policy and access instructions.
Check the downloaded CSV’s integrity
The metadata file inside the ZIP records this SHA-256 checksum for ActuallyCleanData_2020_ZCTA_to_County_Crosswalk.csv. A matching checksum confirms identical CSV bytes.
9cbe78084635ed120e6808891d99101a58ea9a3543044e7b57596a15abb8635dREADY TO PUT IT TO WORK?
2020 Census ZCTA → County Crosswalk
$29 USD · one time · 46,960 relationships