PlainZIP

Our Methodology

Download the state-level summary (CSV) , open extract wired into this page's Dataset JSON-LD.

Data Sources

PlainZIP draws from authoritative, publicly available federal sources:

Processing Pipeline

We pull ACS 5-Year Estimate data from the Census Bureau API for every ZCTA and process it as follows:

  • Extracts demographic variables (population, age distribution, ethnicity).
  • Extracts income variables (median household income, per capita income, poverty rate).
  • Extracts education attainment variables (high school, bachelor's, graduate degree completion rates).
  • Extracts housing variables (owner/renter mix, median home value, median rent, vacancy rate).
  • Merges geographic metadata from simplemaps and HUD crosswalk to assign city, county, state, and time zone to each ZCTA.
  • Joins Census ZIP Code Business Patterns establishment and employment counts by ZIP and NAICS industry, where published.
  • Joins FHFA House Price Index annual appreciation and index values by five-digit ZIP, where published.
  • Computes percentile rankings nationally and within state for key metrics.

Populations (do not mix without disclosure)

PlainZIP keeps multiple federal extracts side by side. Each has its own row universe; treating them as one denominator invents coverage that none of the sources claim:

  • ACS ZCTA demographics: 33,099 ZIP Code Tabulation Areas across 52 jurisdictions (the 50 states, the District of Columbia, and Puerto Rico, not the five inhabited territories), 27,619 cities, and 3,212 counties (summed ZCTA population 312,447,629).
  • Census ZIP Code Business Patterns (ZBP): 34,953 ZIP rows with establishment/employment/payroll fields. Only 30,507 of those ZIPs also carry an ACS ZCTA profile in this extract, ZBP is larger than the ACS set and is not a strict subset.
  • Scorecard / dashboard county feeds (HUD FMR, FBI UCR, DOL childcare) join on county geography at their own vintages, see cross-stage vintages below. Never divide a ZBP count by an ACS count (or the reverse) without naming both populations in the same sentence.

ZIP Codes vs. ZCTAs

ZIP codes are postal routing designations maintained by USPS. ZIP Code Tabulation Areas (ZCTAs) are approximate Census geographic units that correspond to ZIP codes. They are not identical - some postal ZIP codes have no corresponding ZCTA, and ZCTA boundaries are generalized from Census block assignments rather than exact USPS postal boundaries.

PlainZIP uses ZCTAs as its primary geographic unit because they are the Census-defined areas for which ACS data is published. Postal ZIP codes are mapped to ZCTAs via the HUD USPS crosswalk.

Margins of Error

ACS 5-Year Estimates are surveys, all values are statistical estimates with margins of error. For ZIP codes with small populations, margins of error can be significant. PlainZIP displays the survey estimates as published by the Census Bureau; margins of error are available in the raw Census data for users who need them.

Data Collection Method

The American Community Survey is conducted continuously by the Census Bureau, surveying approximately 3.5 million households annually. ACS collects detailed demographic, social, economic, and housing data through a combination of mail, internet, telephone, and in-person interviews. The 5-Year Estimates pool five years of survey responses to produce reliable estimates for small geographic areas, including ZIP Code Tabulation Areas. Because the ACS is a survey (not a census), all published values are statistical estimates with associated margins of error. Larger ZCTAs with more respondents produce more precise estimates, while smaller ZCTAs may have wider margins of error.

Update Schedule

The Census Bureau publishes new ACS 5-Year Estimates annually, typically in December. Each release reflects the most recent five-year survey period. We update our database within 30 days of each new Census release. Between releases, demographic changes from migration, development, and economic shifts are not reflected in our data. ZIP Code Business Patterns is republished by the Census Bureau annually (typically mid-year); the FHFA House Price Index is republished quarterly. We refresh both on the same rolling cadence as our ACS updates rather than on their exact release days.

Download the Data

Free to reuse with attribution under CC BY 4.0: download the state-level summary (CSV). Same total ZIP counts, population, and average income/home-value/median-age figures every state page renders, for all 52 jurisdictions covered (50 states + DC + Puerto Rico). Cite PlainZIP and the underlying Census/HUD/FHFA sources named on this page. Commercial data licensing, API access, and bulk extracts beyond this CSV are not activated.

Scorecard & Composite Grade Methodology

The Affordability Dashboard's composite scorecard grade combines seven weighted dimensions, each computed directly from the raw federal figures with no editorial adjustment: Income 20%, Safety 20%, Housing 15%, Rent 15%, Education 10%, Commute 10%, and Childcare 10%. Every underlying raw field (household income, crime rate, home value, rent, school metrics, commute time, childcare cost) is sourced from the agencies listed above. The scorecard grade itself is PlainZIP's own transparent derived index built from those sources - it is not an official rating from the Census Bureau, HUD, the FBI, or the Department of Labor, none of which publish a combined affordability score.

Rent and childcare grades are cross-vintage joins: HUD Fair Market Rent (FY2024) or DOL NDCP infant-care cost divided by ACS median household income (2019–2023 5-year). Safety uses FBI UCR counts and population from the same county_crime row (latest year available). Those ratios are exploratory convenience metrics, they do not claim every agency shares one fiscal year or category set. Homepage Dataset temporalCoverage spans 2019/2024 to cover ACS through HUD FY2024 honestly.

Limitations

  • ACS 5-Year Estimates represent a rolling average over five years, not a point-in-time snapshot. Rapidly changing neighborhoods may show lagging data.
  • Not all postal ZIP codes have a corresponding ZCTA, PO Box ZIP codes and some special-purpose ZIP codes have no Census geographic equivalent.
  • Margins of error can be significant for small-population ZCTAs. PlainZIP displays the estimates as published; check the underlying Census data for confidence intervals.
  • City and county assignments use the HUD crosswalk, which maps each ZIP to its dominant county, ZCTAs spanning multiple counties are assigned to the county covering the majority of addresses.

Monetization and partnership readiness

Readiness only; nothing below activates revenue without operator review. PlainZIP is in the AdSense getting-ready queue for display advertising. If approved, ad units would follow Module 36 density ceilings and would never sit adjacent to interpretive financial or housing advice (this site publishes geo-registry figures and transparent composite indexes derived from named federal sources). YMYL-compliant affiliate or referral placements are not live; any future activation would require clearly labeled, non-advice adjacency and operator sign-off. Alternative ad-network eligibility paperwork may be prepared against standard geo-data publisher criteria (for example Media.net content guidelines), but activation remains operator-gated.

Not Affiliated

PlainZIP is not affiliated with the U.S. Census Bureau or any government agency. We are an independent portal that transforms publicly available government data into an accessible format.

This page explains the source records, calculation, and limits behind the figures shown. Methodology pages document source joins and derived indexes. Raw ACS/HUD/ZBP fields are unchanged; composite scorecard grades are PlainZIP formulas over those fields. Read our editorial standards and corrections policy, the methodology behind these numbers, or report a data error. Data current as of the ACS 2019–2023 claims window.