Frequently Asked Questions
Common questions about ZIP code data, Census estimates, and how to use PlainZIP.
Where does PlainZIP get its data?
PlainZIP uses U.S. Census Bureau American Community Survey (ACS) 5-Year Estimates (2023) for all demographic, income, education, and housing data. Geographic metadata (city/county mapping, coordinates, time zones) comes from simplemaps.com and the HUD USPS ZIP-to-county crosswalk.
What is the American Community Survey (ACS)?
The ACS is an ongoing nationwide survey conducted by the U.S. Census Bureau that collects information on demographics, income, education, housing, and other characteristics. The 5-Year Estimates pool 5 years of survey responses to provide reliable data for small geographic areas like ZIP codes, which have too few responses for reliable single-year estimates.
What is the difference between a ZIP code and a ZCTA?
ZIP codes are postal routing codes maintained by USPS. ZIP Code Tabulation Areas (ZCTAs) are approximate Census geographic units created to correspond to ZIP codes. They are not identical, ZCTA boundaries are generalized from Census block assignments rather than exact USPS boundaries. PlainZIP uses ZCTAs because they are the units for which Census survey data is published.
Why does the data for my ZIP code look different from other sources?
ACS estimates are statistical survey estimates with margins of error, not exact counts. Different time periods, different ACS releases, or different methods of aggregating Census geographic units can produce different results. PlainZIP uses ACS 2023 5-Year Estimates. For ZIP codes with small populations, estimates have wider margins of error.
What does median household income mean?
Median household income is the income level at which half of all households in the ZIP code earn more and half earn less. It is a measure of the typical income level in an area. It is different from average (mean) income, which is pulled higher by very high earners. Median income is generally a better measure of what a 'typical' household earns in an area.
What data is included in the education category?
Education attainment data shows the percentage of adults 25 years and older who have achieved various education levels: less than high school, high school diploma or GED, some college or associate degree, bachelor's degree, and graduate or professional degree. These come from ACS Table B15003.
How current is the data?
PlainZIP uses the 2023 ACS 5-Year Estimates, which pool survey data from 2019 through 2023. The Census Bureau releases new 5-Year Estimates annually in December. We update our database when new annual releases become available.
Does PlainZIP include business or commercial data?
No. PlainZIP focuses on residential demographic, income, education, and housing data from the ACS. It does not include business counts, commercial property data, or economic establishment data.