I am looking for Zipcode data with the +4 digits at the end for a City (I can use it by state and clip the points to my municipal boundary). I called the post office and had no luck (national customer center in Memphis, TN- claimed that their +4 ZIP Code GIS Layer is not for the public).

Would anyone know where I could find this data?

  • Comments are not for extended discussion; this conversation has been moved to chat. – Midavalo Mar 29 '17 at 21:33
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  • Zipcodes are linear and/or point (PO Box) features, not polygons. – Vince Mar 30 '17 at 1:28
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    @Vince Who said anything about polygons? – NULL.Dude Mar 30 '17 at 13:23
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    @Joe The USPS updates the AIS/AMS datasets every month; so you have a risk of having out of date data. For roughly $40.00 I believe you can subscribe to it from the USPS. – D.E.Wright Apr 11 '17 at 21:37

Some background: The USPS maintains zip codes as sets of delivery zones(5 digit) and routes(+4 digits), usually along streets with address boundaries. USPS does not maintain zip codes in any shape format.

I had the issue of finding a viable source as well. I narrowed my possible solutions to the following 4 and chose to go with #3.

  1. You can download the 5 digit data from https://www.census.gov/geo/maps-data/data/tiger-line.html but the +4 data is not available from census or from the post office with +4 data.

  2. Depending on how large your AOI is you can use the tool https://eddm.usps.com/eddm/customer/routeSearch.action to search zips. It will show the +4 routes which can be heads up digitized.

  3. There are several companies that will sell you very accurate zip code data, Maponics being the one that I use. The five digit zip codes from them are pretty accurate. They do not offer zip+4 boundaries but they do have centroids for the +4 routes.

  4. Your other option would be to request the address based data from USPS and attempt to create spatial data for it using parcels with addresses and streets as reference layers, though this would likely open a whole other can of worms.

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  • 1. Wont work I need the +4 2. My AOI is entire City do not have the time to get every address zip+4. 3. Unfortunately this may be my only option. 4. This was my original plan when I contacted USPS, they have zip+4 GIS Layer but wont give it out its public information I don't see what the big deal is. – NULL.Dude Apr 12 '17 at 12:17
  • The interpretation of public information differs between government entities as well as between areas and levels of government. Some states/counties and entities have very lenient rules pertaining to what data can be released and the process for releasing it. Others place exceptions on certain types of data or require "processing fees" and security clearances for it to be released. – Kingfisher Apr 12 '17 at 15:07

The plus 4 value is based on the address there is not a single number for a city. It is not a universal number for a region as the first 5 digits are https://www.zip-codes.com/learn-about/what-is-a-zip-4-code.asp . You will need to calculate it against some tiger data if you are trying to get every unique value and tie it to a region.

It would be relatively easy to scrape the values you want against this web services https://www.zip-codes.com/search.asp

Additionally, what you are asking for probably does not exist because it's not a requirement for delivery and was not universally accepted... not all address have a +4: Source https://en.wikipedia.org/wiki/ZIP_Code#ZIP.2B4

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  • FYI, the first 5 digits are not a universal number for a region. That's why ZCTAs were created. – Dan C Apr 11 '17 at 21:46
  • Yeah universal might not be the right word. the first 5 covers an area the last 4 is for a point. – risail Apr 11 '17 at 21:48
  • the GIS Layer does exist which is why I am asking for it here. USPS has it but they claim its not for the public.... but the information itself is public information nothing "classified" hoping someone knew of another source. – NULL.Dude Apr 12 '17 at 12:20
  • Maybe you should try asking this on opendata stack. Your asking for a data source not a "GIS how to" might have better luck there. – risail Apr 12 '17 at 12:43

The ZipPlus4 information seems to be available in the (old) Tiger/Line 2000 data. e.g. ftp://ftp2.census.gov/geo/tiger/tgrcd108/FL/tgr12099.zip for Palm Beach County, FL.

According to gdal driver documentation,

Feature Representation Following is a list of feature types, and their relationship to the TIGER/Line product.


A CompleteChain is a polyline with an associated TLID (TIGER/Line ID). The CompleteChain features are established from a type 1 record (Complete Chain Basic Data Record), and if available it's associated type 3 record (Complete Chain Geographic Entity Codes). As well, any type 2 records (Complete Chain Shape Coordinates) available are used to fill in intermediate shape points on the arc.



These features are derived from type Z (ZIP+4 Codes) records. ZipPlus4 features have a many to one relationship with CompleteChain features.

However, the linked Tiger/Line 2000 data is in report type (.RT) files format, not in current GIS format.

Here are some example output for running ogrinfo TGR12099.RT1 ZipPlus4:

  MODULE (String) = TGR12099
  TLID (Integer) = 115356454
  RTSQ (Integer) = 0
  ZIP4L (Integer) = 3366
  ZIP4R (Integer) = 3367

  MODULE (String) = TGR12099
  TLID (Integer) = 115356457
  RTSQ (Integer) = 0
  ZIP4L (Integer) = 6048
  ZIP4R (Integer) = 6049

  MODULE (String) = TGR12099
  TLID (Integer) = 115356460
  RTSQ (Integer) = 0
  ZIP4L (Integer) = 2680
  ZIP4R (Integer) = 5151

  MODULE (String) = TGR12099
  TLID (Integer) = 115356485
  RTSQ (Integer) = 0
  ZIP4L (Integer) = 0
  ZIP4R (Integer) = 0

(Note: the TLID represents "complete chains" or arcs in the network). The complete chains are topologically correct according to the meta data:

  • Complete chains must begin and end at nodes.
  • Complete chains must connect to each other at nodes.
  • Complete chains do not extend through nodes.
  • Left and right GT-polygons are defined for each complete chain element and are consistent throughout the extract process.

There is an GIS.SE question (Anyone who has the ESRI Census 2000 Tiger/Line data?), which has an answer describing a script for converting the .RT files to shapefiles. I haven't tested it myself, but the code may be relevant.

Also, USPS really defines the ZIP(+4) codes etc. and may change it over time, so the Tiger/Line 2000 from census data may be outdated. Also, I am not an expert with Tiger data. You might want to check with the US Census/Tiger-line people to see if the ZipPlus4 is available in the current tiger-line files in GIS format.

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  • This data is far too old for me to use – NULL.Dude Apr 17 '17 at 14:07
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    @Joe, as I said You might want to check with the US Census/Tiger-line people to see if the ZipPlus4 is available in the current tiger-line files in GIS format. Historically, it's there in older formats. – tinlyx Apr 17 '17 at 14:24

A common misconception is that zip codes are areas, when in fact they are routes. You can conceptualize the area these routes occupy and make your analysis that way, but many people will see this as a flawed or problematic analysis especially if your data type conflicts with or exaggerates error created by that flawed understanding of zip codes.

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  • That is a valid comment; but doesn't help address the question posed since he didn't provide a good use-case for needing the values. – D.E.Wright Apr 11 '17 at 23:34

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