zlacker

>>voxada+(OP)
To put it in plain mathematical language, ZIP codes are not defined as polygons [0]. The consequence is that performing any analysis with an assumption that ZIP codes are polygons is bound to be error-prone.

0: https://manifold.net/doc/mfd8/zip_codes_are_not_areas.htm

>>jihadj+t7
Yeah. ZIP codes are sets in the abstract-dimensional space of carrier delivery points. I suppose you could think of them as lines, but definitely not polygons.

>>mholt+rf
Zip codes (in the US) are machine readable numbers a mail sorter can use to send a parcel to the right delivery truck for final delivery. In the US, they represent the hierarchy of postal centers with the most significant digit representing the primary hub for a region and the smallest number the actual post office that will be in charge of delivering the letter (or truck if you do the extended post code).

They don't represent geography at all, they represent the organizational structure of USPS.

They work by making the address on a letter almost meaningless. For some smaller population zip codes you can practically just put the name and zip code down and achieve delivery.

>>cogman+ci
Right but this ends up being a good approximation for geography because the reality of logistics is that you end up doing a cute n-ary search of the geography. When you know the regional hub you can say for certain a huge chunk of the US the zip code doesn't represent. And then you keep n-secting. Sometimes the land-mass you get at the end is specific enough for your uses.

You're not going to wind up with a situation where zip codes with the same regional marker end up on different coasts.

>>Spivak+Xr
> You're not going to wind up with a situation where zip codes with the same regional marker end up on different coasts.

Couldn't this happen for military or proxy codes (PO boxes or other) ?