According to the accepted answer of Determining which US zipcodes map to more than one state or more than one city?, there are only 13 zip codes in two states. Reading down further on the page, though, you can see that back in 1994, there were 153 zip codes that cross state boundaries. That response doesn't actually tell you what the 153 anomalous parties are, though. Another response right above that one from 2016 found and listed 93 multi-state zip codes, but is missing at least one code that I know of.

The more correct answer of 153 is still quite dated, though, so I resubmit the question - how many US Zip codes span state boundaries and what are they?

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Unless you work for the USPS and/or deliver mail you should avoid using zip codes for anything analytical. They change almost daily, and are actually not polygons, but household points, but vendors continue to draw polygons around them and call them 'zip code boundaries'.

You'll find numerous sources of zip code polygons, all of which are different - Google, USPS, ESRI, Census/TIGER all show differences in the boundaries.

Here's a great article by CARTO about not using zip codes: https://carto.com/blog/zip-codes-spatial-analysis/

  • I don't work for USPS; I found that question while attempting to resolve omissions in a database filled with customer information. We have several records with zip codes that don't have states filled out and need to complete a list of addresses prior to shipping stuff. Until yesterday, I didn't even know there were zip codes that spanned state borders. I'd always assumed that the state-zip code relationship was 1:many. (Guess the adage about assumptions applies). Anyway, thanks for the article reference. Also, question stands- is there a definitive list of multi-state zip codes anywhere? – Brad Nov 26 '19 at 20:23
  • best source I can think of is CENSUS/TIGER: census.gov/geographies/mapping-files/time-series/geo/… but you'll have to put STATE and ZCTA files together – DPSSpatial_BoycottingGISSE Nov 27 '19 at 14:22

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