I sent a letter from the UK to the US, but I wrote the address from memory, and like a doof, used my brother’s old, not current zip code. Same city, wrong zip.
What are the chances it will still reach its destination? How long might it be delayed? Will the USPS still deliver it to the (correct) street address, or will it be binned because the address doesn’t match the zip?
If it doesn’t show up is there any sort of procedure my brother could use to locate it?
It will get there, just be delayed a little bit. The automated sorting will try to send it to the city with the ZIP you used but won’t be able to find the address so it will be kicked out for ‘further attention’.
If it’s a common address, like ‘220 Main Street’ or something that might be in the city of that ZIP code it may get to the carrier who will likely catch the error at delivery time.
It certainly will not be automatically thrown away for a ZIP not matching address!! Technically speaking, the ZIP code is optional; it just takes longer to be delivered without it. I can’t find a cite for confirmation, but I believe once it is kicked out of the automated process, the city-state combination would take priority, on the theory that few people accidentally write “Andover, MA” when they mean “Salem, MA” but it’s rather easy to write “01812” when you mean “01817.”
It should get there eventually. How long it will take is anyone’s guess. I’ve experienced delays from a day or two to several weeks.
Precisely. I once received a letter destined for Michigan that had an Arizona zip code, IIRC, and it was delayed a couple of weeks. But with USPS you can never really predict it.
I wish my biz partner was here, he worked at the places that do the corrections. They are called Remote Encoding Centers. Basically, when a piece of mail is unreadable or has conflicting information the sorting machine takes a picture of it and sends it electronically to the REC. The REC has teams of people who then manually input the corrected address from the image and a code is then printed on the mail piece so the next sorting machine knows what to do with it.
Cool, thanks. I am reassured.
Just a little additional note:
In the ‘old’ (pre-automation) days your mailpeice would probably get to the right place a little quicker. If a wrong-address peice did get to us (the carriers) it would be caught while we were casing (putting the mail in order for delivery) the mail and sent back to the clerks and it would be on its way to the right destination that afternoon. Modern automation puts most of the letter mail in delivery order before it gets to the carrier (DPS, for Delivery Point Sequencing) and it’s not actually seen until the carrier gets to the delivery point. This delays everything by at least a day, and also introduces the possibility that a carrier not familliar with the route may not catch it so it won’t come back for at least another day…if at all.
One of the dirty little secrets of ‘new and improved’, lol.
The above answers are correct assuming it’s first class mail, and you did give City and State.
Why not just send another copy, with the right address?
I recently sent a thank-you card to my parents with the wrong zip code, and it came back to me the next week as “Street does not exist.” I corrected the zip code and sent it again, and it made it.
When I first moved to L.A., my mom sent me a letter from Torrance, about 14 miles away. It took two weeks to reach me.
She had my address and ZIP code right, but she’d put Culver City (a few blocks away) for the city instead of Los Angeles.
Just to reassure the OP - the Post Office takes legendary pride in delivering every letter to its intended recipient, regardless of how badly it may be addressed.
My mom once received a letter sent to
Velma Miller
Follett, TX
That was her maiden name, and she lived in Oklahoma. Fortunately in Follett (population < 1000) the mail clerk knew her, and corrected it and sent it on 
Gotta love small towns!