Data Methodology
How we source, process, and present ZIP code data
Overview
ZipCodeFacts aggregates publicly available data from authoritative government and research sources to create comprehensive ZIP code profiles. We do not conduct original surveys or field research. Our role is to compile, organize, and present existing public data in an accessible format.
Primary Data Sources
U.S. Census Bureau — American Community Survey (ACS)
The ACS is conducted annually by the U.S. Census Bureau and provides estimates for population, median household income, age demographics, and other socioeconomic indicators at the ZIP Code Tabulation Area (ZCTA) level.
- • Fields: Population, median household income, geographic coordinates
- • Typical lag: 12–24 months from collection to release
- • Source URL: census.gov/programs-surveys/acs
Zillow Home Value Index (ZHVI)
ZHVI reflects the typical home value for a given area, smoothed and seasonally adjusted. Zillow publishes this data monthly at the ZIP code level. We use the “All Homes, Time Series, Smoothed, Seasonally Adjusted” dataset.
- • Fields: Median home value, year-over-year appreciation, 5-year appreciation
- • Update frequency: Monthly
- • Source URL: zillow.com/research/data
USDA Rural-Urban Commuting Area (RUCA) Codes
RUCA codes classify U.S. ZIP codes by their urbanization and commuting characteristics. We use these codes to categorize areas as Urban, Suburban, Rural, or other classifications.
- • Fields: Area classification (Urban, Suburban, Rural, Small Town)
- • Source URL: ers.usda.gov/data-products/rural-urban-commuting-area-codes
OpenDataSoft / USPS
County assignments for ZIP codes are sourced from USPS data via OpenDataSoft. ZIP-to-county mapping provides additional geographic context.
- • Fields: County name
- • Coverage: ~90% of ZIP codes
Scoring Methodology
ZipCodeFacts calculates composite scores (0–100 scale) to help users compare ZIP codes. All scores are derived from publicly available data and use transparent, documented algorithms.
ZIP Score
A general livability score based on weighted factors including median income relative to cost of living, population stability, housing affordability, and area classification. Higher scores indicate stronger overall livability metrics.
Affordability Score
Measures how affordable a ZIP code is based on the ratio of median home value to median household income, compared to national and state averages.
Data Quality Score
An internal metric measuring data completeness for each ZIP code. ZIP codes missing population, income, or housing data receive lower quality scores, and very low-quality pages are excluded from search engine indexing.
Important: Scores are statistical calculations, not endorsements or predictions. They do not account for hyperlocal factors such as individual neighborhood safety, school quality, or environmental conditions. Past data trends do not guarantee future outcomes.
Data Processing & Updates
Our data pipeline follows these steps:
- 1.Import: Raw data is downloaded from official source websites (Census, Zillow, USDA).
- 2.Validation: Data is validated for completeness, reasonable ranges, and consistency across sources.
- 3.Matching: Data from different sources is matched by ZIP code and reconciled where discrepancies exist.
- 4.Scoring: Composite scores are calculated using the documented algorithms.
- 5.Publication: Processed data is stored in our database and served to the website.
Known Limitations
- •Data timeliness: Census ACS data is typically 12–24 months old at publication. Zillow data is more current (monthly updates) but reflects modeled estimates, not individual sales.
- •Incomplete coverage: Not all ZIP codes have data for every field. P.O. Box ZIP codes, military installations, and some rural areas have limited or no demographic data.
- •ZIP vs. ZCTA: Census data is published at the ZCTA level, which approximates but does not exactly match USPS ZIP code boundaries.
- •Estimated content: Some sections (weather, transportation, school overviews) use generalized descriptions based on state and area classification, not ZIP-level verified data. These sections are clearly labeled as estimates.
- •AI-generated content: Some sections are generated by AI based on the data in our database. AI content is labeled and should be verified independently.
What We Do Not Provide
- Real-time or live data feeds
- Individual property valuations or appraisals
- School ratings or individual school performance data
- Crime statistics at the ZIP code level
- Financial, legal, or real estate advice
- Guaranteed predictions about future property values or demographic trends
Corrections & Feedback
If you find data that appears inaccurate or have questions about our methodology, please let us know through our contact page or use the “Report Data Issue” button on any ZIP code page. We review all reports and correct verified errors. See our editorial policy for more details.
For the full legal disclaimer, see our Disclaimer & Data Sources page.