Re:USPS now offers official ZIP Code boundary polygons
by Tangurena2 on Monday November 09, 2026 @04:29PM
(#50432457)
Also, there are a few zip codes that cross state boundaries. Those rare cases involve very rural areas where the nearest post office is across the state line.
The +4 bit of the zip code narrows the location down to a block or street. In the case of apartment/condo buildings, each bank of mailboxes (for each lock that the mail carrier uses) gets their very own +4.
Re:USPS now offers official ZIP Code boundary polygons
by peezd on Monday November 09, 2026 @04:56PM
(#50432826)
This gave us such a headache 20 years ago in earlier ecommerce days. One of many edge cases. I'm in Colorado so we always tested with 82082 which covers areas in WY, NE, and CO.
The +4 bit of the zip code narrows the location down to a block or street. In the case of apartment/condo buildings, each bank of mailboxes (for each lock that the mail carrier uses) gets their very own +4.
Sample picture: https://postalsupply.net/2023/03/maintenance-and-upkeep-tips...