USPS now offers official ZIP Code boundary polygons

Re:USPS now offers official ZIP Code boundary polygons by ortusdux on Monday November 09, 2026 @03:33PM (#50431638)

I'm sure their system has its faults, but I find shipping to the UK via postal code quite easy.

"A full postcode identifies a group of addresses (typically around ten) or a major delivery point."

https://en.wikipedia.org/wiki/Postcodes_in_the_United_Kingdo...

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Re:USPS now offers official ZIP Code boundary polygons by reaperducer on Monday November 09, 2026 @03:39PM (#50431734)

"A full postcode identifies a group of addresses (typically around ten) or a major delivery point."

The United States can be more granular, as a "full postcode" equivalent in the United States is ZIP+4, which can resolve down to an individual building, mailbox, or person, depending on the characteristics of the location.

https://en.wikipedia.org/wiki/ZIP_Code#ZIP+4

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Re:USPS now offers official ZIP Code boundary polygons by twodave on Monday November 09, 2026 @03:43PM (#50431801)

And even for those where it isn’t one exact person/box there is a 2 digit delivery point code that often is included on the end.

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Re:USPS now offers official ZIP Code boundary polygons by cjs_ac on Monday November 09, 2026 @03:47PM (#50431866)

Interestingly, there are no polygons for UK postcodes, because UK postcodes don’t represent a geographical area; instead, they represent one or more discrete points.

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Re:USPS now offers official ZIP Code boundary polygons by EwanToo on Monday November 09, 2026 @03:54PM (#50431983)

I know what you're saying, but Ordnance Survey sells the polygons anyway.

https://docs.os.uk/osngd/data-structure/administrative-and-s...

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Re:USPS now offers official ZIP Code boundary polygons by cjs_ac on Monday November 09, 2026 @04:28PM (#50432439)

That’s naughty of them. I wonder how SW1A 1AA (Buckingham Palace) and SW1A 0AA (the House of Commons) are represented.

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Re:USPS now offers official ZIP Code boundary polygons by xp84 on Monday November 09, 2026 @04:10PM (#50432200)

ZIPs don't represent areas either. They represent routes, so a collection of paths on a road map is bundled together and named with a ZIP. If you built a new house in between towns, whichever post office decides to serve it would extend one of their lines to go past your house, and then you are assigned that ZIP code. Since it's all based on their convenience, they don't pay any mind to things like city limits or even in some cases state lines.

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Re:USPS now offers official ZIP Code boundary polygons by russdill on Monday November 09, 2026 @04:29PM (#50432459)

Given how postcodes are supposed to work, this is what I would expect. Curious if many of the polygons in the data set contain more than one polygon and or if there is any overlap

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Re:USPS now offers official ZIP Code boundary polygons by kube-system on Monday November 09, 2026 @04:45PM (#50432699)

> how postcodes are supposed to work

Not sure under what basis you think they are "supposed" to be a certain way but postal codes originated as a signifiers of areas, even in the UK.

US postal codes absolutely have overlap in area, because they do not divide land, they direct delivery routing.

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Re:USPS now offers official ZIP Code boundary polygons by russdill on Monday November 09, 2026 @05:46PM (#50433389)

Different places have things like postal codes that mean different things, but in the US postal codes are tied to mail delivery routes.

https://web.archive.org/web/20030119031055/http://users.rcn....

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Re:USPS now offers official ZIP Code boundary polygons by kube-system on Monday November 09, 2026 @06:06PM (#50433641)

Yes, I know that is the current way they work (...and I said it in my comment?)

My point is that postal codes aren't "supposed" to work any particular way. They work in what ever way they are specified to work at any particular point in time in any particular place.

Zip codes in the US are related to delivery routes. Prior postal codes in the US were not.

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Re:USPS now offers official ZIP Code boundary polygons by russdill on Monday November 09, 2026 @06:40PM (#50433968)

In the US they were always tied to routes. The first number gives a set of distribution centers, and the second two numbers where specifically to go. If you look at a map of the first number, you'll see sharp lines separating the states. It'd be hard to verify historically, but if you look at zip codes near the border for, say, 89439, several addresses on the California side use the 89439 zip code.

It'd find it difficult to believe that when the system was originally created, mail delivered by a Nevada post office to a physical location in California had a zip code starting with a 9 rather than an 8.

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Re:USPS now offers official ZIP Code boundary polygons by kube-system on Monday November 09, 2026 @06:53PM (#50434116)

Zip codes were always tied to routes. Postal codes in the US pre 1962 were not.

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Re:USPS now offers official ZIP Code boundary polygons by reticulates on Monday November 09, 2026 @03:57PM (#50432019)

Fun fact, a postcode can represent up to 100 addresses, apartment buildings with more than 100 units have multiple postcodes. Sometimes third-party systems will only recognize a subset of those postcodes (e.g: a system might assume a building only has 1 postcode) which can lead to some residents being in the geographic region for a service while others are not despite being in the same building.

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Re:USPS now offers official ZIP Code boundary polygons by cornedor on Monday November 09, 2026 @04:17PM (#50432286)

As someone from the Netherlands I’ve been very surprised at how far “ahead” we seem to be here. Just a postcode can point you to a street, even the side of the street (right or left hand), a house number than gives you the exact building. That is how people are used to enter their address here.

When I had to work with addresses in other countries, I found out that is not that normal.

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Re:USPS now offers official ZIP Code boundary polygons by ortusdux on Monday November 09, 2026 @06:44PM (#50434022)

In the US, outside of grid systems, it's common for house addresses to be distances, with even numbers to be on the right hand side. For example, 567 Oak Street would be 0.56 miles down Oak, on the left. Very helpful for first responders and delivery people. Not that helpful if you do not know where Oak street is.

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