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#US ZIP CODE BOUNDARIES ZIP#
#US ZIP CODE BOUNDARIES DOWNLOAD#

#US ZIP CODE BOUNDARIES ZIP#

For the ZIP Codes that don’t have a corresponding area (the PO Box clusters and large organizations), these essentially represent points that fall within ZCTA polygons.

The UDS Mapper project publishes a ZIP Code to ZCTA Crosswalk file that lists every ZIP Code and the ZCTA it is associated with. To prevent this from happening, you can aggregate your ZIP Code data to ZCTAs prior to joining it to boundary files or other datasets. As census blocks are aggregated into ZCTAs based on the predominate ZIP Code for addresses within the block, these non-areal ZIPs fall out of the equation and we’re left with ZCTAs that approximate ZIP Codes for delivery areas.Īs a result, if you’re trying to match either your own summarized address data or sources that use ZIP Codes as the summary level (such as the Census Bureau’s Business Patterns and Economic Census datasets), some ZIP Codes will not have a matching ZCTA and will fall out of your dataset. Some ZIP Codes represent large clusters of Post Office boxes or are assigned to large organizations that process lots of mail.

#US ZIP CODE BOUNDARIES DOWNLOAD#

You can download ZCTA boundaries from the TIGER / Line Shapefiles page, and there is also a generalized cartographic boundary file for them. ZCTAs are delineated once every ten years in conjunction with the decennial census, and data from the decennial census and the 5-year American Community Survey (ACS) are published at the ZCTA-level. After this initial assignment, they make some modifications to aggregate or eliminate orphaned blocks that share the same ZIP number but are not contiguous. The Bureau assigns census blocks to a ZIP number based on the ZIP that’s used by a majority of the addresses within each block, and aggregates blocks that share the same ZIP to form a ZCTA. The US Census Bureau creates areal approximations for ZIP Codes called ZIP Code Tabulation Areas or ZCTAs.

When we see ZIP Code boundaries (on Google Maps for example), these have been derived by creating areas where most addresses share the same ZIP Code. They are simply numbers assigned to ranges of addresses along street segments, and the codes are associated with a specific post office. Otherwise codes that have leading zeros get truncated, and the code becomes incorrect.Ĭontrary to popular belief, ZIP Codes are not areas and the US Postal Service does not delineate boundaries for them.

ZIP Code and ZCTA numbers must be saved as text in data files, and not as numbers.

Analyzing data at either the ZIP Code or ZCTA level over time is difficult to impossible.

They vary tremendously in size, shape, and population.

ZIP Codes were designed for delivering mail, not for studying populations.

This can make selecting and downloading ZIP Code data for a given area difficult.

ZCTAs do not nest or fit within any other census geographies, and the postal city name associated with a ZIP Code does not correlate with actual legal or municipal areas.

You need to crosswalk your ZIP Code data to the ZCTA-level to prevent this. But ZCTAs are not strictly analogous with ZIP Codes there isn’t a ZCTA for every ZIP Code, and if you try to associate ZIP data with them some of your records won’t match.

The Census Bureau publishes population data by ZCTA and boundary files for them.

The Census Bureau has done this in creating ZIP Code Tabulation Areas (ZCTAs).

Areas must be derived using address files.

ZIP Codes are actually not areas with defined boundaries, and there are no official USPS ZIP Code maps.

I’ll cover the following issues in detail: The longer story: if you’re trying to associate ZIP Code-level data with census ZCTA boundary files or demographic data, there are caveats. Use any census data provider to get ZCTA data:, Census Reporter, Missouri Census Data Center, NHGIS, or proprietary library databases like PolicyMap or the Social Explorer. The short story is: you can get boundary files and census data from the decennial census and 5-year American Community Survey (ACS) for ZIP Code Tabulation Areas (ZCTAs, pronounced zicktas) which are approximations of ZIP Codes that have delivery areas. In this post I’ll summarize these challenges and provide some solutions. However, there are a number of challenges associated with using ZIP Codes as a unit of analysis that most people are unaware of (until they start using them). ZIP Codes are commonly used for summarizing address data, as it’s easy to do and most Americans are familiar with them. Since the COVID-19 pandemic began, I’ve received several questions about finding census data and boundary files for ZIP Codes (aka US postal codes), as many states are publishing ZIP Code-level data for cases and deaths.