8

I am testing a solution for a tax calculation system, and some states have zip code ranges with specific taxes, so I need to know if there are zip codes that correspond to different locations. One part of the system uses different combinations of city/zip to find the county, because some locales have taxes that vary by county.

Are there zip codes that correspond to more than one location but are separate from each other, possibly in different states or counties?

I know that a zip code can span cities and/or states but I want to know if there are zip codes that are completely autonomous of one another but share the same code.

Is there a way that I can find up-to-date information about this?

  • Please define "duplicate". Are you asking if two different cities can have the same zip code? Perhaps you want to know if one area can be called two different things, but have the same zip code? Are you asking if one zip code can be in two different counties? Are you asking if you can have the same zip code in a different state? Are you asking if one geographic area (say a certain building) can have two different codes? How "duplicate" do you mean? Have you Googled or read Wikipedia to better understand a Zip Code? – Keeta May 8 '18 at 18:31
  • @Keeta, I apologize for being ambiguous with my question, I know that a zip code can span cities and/or states but I wanted to know if there are zip codes that are completely autonomous of one another but share the same code. – Malachi May 8 '18 at 18:35
  • Suggest relating...I think this question would have been answered by reading the detailed answer in: gis.stackexchange.com/questions/53918/… – Keeta May 8 '18 at 18:42
  • I actually read that thread, and didn't find the answer that I was looking for, @Keeta – Malachi May 8 '18 at 18:44
19

There are no duplicate ZIP Codes. There are some ZIP Codes that are multi-part polygons, but those polygons are usually adjacent.

Source: I manage/update ZIP Codes for the USPS

  • In Pennsylvania, the Post office boundaries do not align with the township boundaries, like Saylorsburg PA, is part of Ross Twp, Hamilton twp, and Chestnuthill Twp, so the taxing and PO do not align. You also had multiple township using the same Post Office Like Clifton Twp, Covington Twp, and Thornhurst all using the same zip code as Gouldsboro, PA. I worked with the townships and Post Office on 911 addressing for this. – Bill Chappell May 8 '18 at 17:55
  • Looking at the authoritative data, there are 39084 ZIP Code boundaries – Maksim May 8 '18 at 18:00
  • you said, usually adjacent, what about when they are not adjacent? – Malachi May 8 '18 at 18:10
  • Then they are across the road from each other typically, very close – Maksim May 8 '18 at 18:13
  • 2
    That is correct – Maksim May 8 '18 at 18:26

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