Mapping counties to zip codes

Question

Is there any freely available data that relates USA zip codes and USA counties (FIPS County codes)?

Since counties can contain multiple zip codes, one can have multiple entries, in such a table:

FIPS_code, county_name, zip_code
36001, Albany County, 12201 
36001, Albany County, 12202
36001, Albany County, 12203
...

The examples above for Albany County can be found here.

Is this data openly available in, perhaps, a csv file or dataset?

Answer 1

You might want to check out the HUD zip code-county crosswalk (screenshot below).

My gut feeling is that this feature would be in the US census TIGER product line https://www.census.gov/geo/maps-data/data/tiger.html maybe here: https://www.census.gov/geo/maps-data/data/relationship.html

Please let us know what you find most useful.

Answer 2

Some other answers hint at this, but the caution to keep in mind is that ZIP codes are not geographies on a map. They are identifiers for postal delivery routes which are often but not always geographic.

To accommodate the intense demand for data aggregated by ZIP code, the Census Bureau created ZIP Code Tabulation Areas (or ZCTAs) which are roughly what most people think of as the geography that matches a given ZIP code. But not all ZIP codes exist as ZCTAs. For example, my office address is in the ZIP code 60208, but it is in the ZCTA 60201. There is no ZCTA for 60208. You could compare the 60208 ZIP code to recently introduced "overlay" area codes.

Census TIGER data can get you most of the way to mapping postal addresses to geographies, but you have to be prepared for certain ZIP codes to not have ZCTAs, and as J. Miller mentioned in a comment above, the TIGER ZCTA data doesn't keep pace with changes to actual ZIP code definitions.

Finally, ZCTAs are not in any way required to be contained within counties. The accepted answer from Blair Christian points to a resource provided by the Census Bureau which breaks down the relationship between ZCTAs and counties (as well as other geographies.) The data format is a bit complex but it tells what percentage of population, housing units, total area and land area of each ZCTA are in each county.

Answer 3

For personal/educational use, US Zip Codes has a free download (*.xlsx and *,csv) that has zip and county. It has fewer fields than the commercial version which is $40 USD.

Neither has FIPS.

Answer 4

There are GIS servers that have county boundary data and zipcode boundary data. Alas, the zipcode layer that I know about does not include county name as an attribute otherwise you could use the ESRI REST API to download a KMZ file.

If it might help, the following map displays both the county and zipcode boundary layers. The map is centered at Kansas city but can be zoomed/dragged anywhere. Or click Menu ==> Search.

http://www.mappingsupport.com/p/gmap4.php?ll=39.066114,-94.591598&z=11&t=m,Zip_code,County&rest=https://gis.usps.com/arcgis/rest/services/EDDM/EDDM_ZIP5/MapServer?name=Zip_code&layers=0&transparent=true&rest=http://services.nationalmap.gov/arcgis/rest/services/govunits/MapServer?name=County&layers=3,13&transparent=true

I am the developer of the Gmap4 enhanced Google map viewer that is displaying the map.

One of the basemaps displays an “all white” basemap which will make the boundary lines more visible.

To learn about working with GIS layers please visit: http://www.mappingsupport.com/p/gmap4_gis-viewer.html#overlays

Answer 5

Here are is a very user-friendly collection of Census geography code crosswalk datasets: https://data.world/nrippner/ansi-geographic-codes

And, a complete collection of ZCTA crosswalk tables: https://data.world/nrippner/zip-code-tabulation-areas-zcta

Answer 6

A free great resource I use: http://download.geonames.org/ You're welcome!