US postal address identifiers (3,5)
I believe the answer is:
zip codes
(Other definitions for zip codes that I've seen before include "Letters and digits in postal addresses to aid sorting" , "Letters and digits added to postal addresses in the US" .)
I've seen this clue in The Times.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free.
Check out my app
or
learn more
about the Crossword Genius project.