[esrauch]

Yeah it should auto fill but not stop you from changing it, best experience 98% of the time.

I just looked it up and apparently there's some cases of zip codes that do go across state lines too, but it's rare.

[ezfe]

There is a canonical full address for every mailbox in the US. Would be curious to see what these houses show.

My experience living in towns that received mail from other towns is your canonical address IS the other town.

[esrauch]

FWIW I have received mail from the USPS in places that had no canonical full address as well. It's not the case in reality that the USPS only delivers mail to mailboxes that have an associated entry in their canonical database here in "messy" reality.