alt Hacker News> Zip+4 codes also change frequently because they aren’t based on locations but on delivery routes and sequencing.
This was news for me. I know the few zip+4 I memorize never change.
I think the source for the parent is AI slop. See [1].
> Due to an increase in population or to the improve postal operations, the US Postal Service® will occasionally add a new ZIP Code or change ZIP Code boundaries.
The plus four digits encode:
> [67] : Sector or Several Blocks
> [89] : Segment or One Side of a Street
Note that this contradicts the parent.
The census bureau (very) periodically publishes zip code data (which is where some places get their geolocation info). If you work with enough addresses you’ll find some zip+4s that are wildly far away from where they used to be. There are paid services that have better accuracy, but I’m not sure how they acquire their data.