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

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

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

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.

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

> 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.

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....

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.

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.

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