I was once told that if you put the Zip Code of the recipient on the same line as you put the City/State, it will be delivered faster than if you put the Zip Code on a line by itself below the City/State line. Is there any truth to this?
P.S. I did search for this, so if it has been previously asked, I apologize.
I’d doubt it. Because mail is a mix of typed and written addresses it all has to be hand sorted. The mail sorters either 1) sort them as they are given to them one by one or 2) have a big pile of letters and grab them one at a time to sort.
If they’re just grabbing them randomly from a pile then maybe writing a BIG or BOLD zipcode in red ink might catch their eye quicker?
But if they have to go through the entire pile during their shift anyway it probably wouldn’t make a diffrence.
On the other hand, an illegible or hard to read zip may slow the speed of your letter.
They put it into a machine first. If the scanner can read it, and the computer can make sense of it, the letter is machine-processed. (much faster) What addresses the computer cannot read, get tossed out to be hand-sorted. (much slower)
So, if you write the address in a format that the computer is expecting, you greatly increase the probability that the machine will be able to do the work.
Below the city/state line, is where the computer expects to see either a bar code or a country name.
Almost all first class letters are not hand sorted. The USPS uses machines that do character recognition to id the zip and put the little bar codes on the bottom front. If the machines can’t figure out the zip, then the letters get routed to a human. And that does take longer.
Typed zip codes are easiest to detect. If you hand write a zipcode, print clearly in as close to a typewriter looking font as you can write. Simple straight lines and curves, close loops, etc. No “personalized” number shapes.
Position of the zip code apparently helps avoid having to go thru humans. My method is to keep it on the same line as city/state but with a little extra space after the state. Keep the whole line as parallel to the edge of the envelope as possible. YMMV.
According to this note on automation from the USPS, even when letters are read by humans, they may not be touched by humans.
I’d wondered why some of the mail I receive has bar codes on the back - now I know.
You can even put the barcode on yourself, for even faster processing, if you have the software to convert the nine-digit zip code to a bar code. I believe this is a feature in newer versions of WordPerfect, for instance. My father typically addresses his mail this way, and it usually makes it across country overnight, even packages.
Microsoft word has that a barcode option when printing labels and envelopes and you can get labelling software from Avery to do the same. My experience is anecdotal but I’ve gotten very fast delivery when I barcode my mail, once even sending mail to Phoenix from a small town 100 miles away and having a payment check deposited that night.
Thanks for the info on barcodes, guys. I’m sure that will be very interesting to many.
… but good luck fitting yourself into a mailbox! 
Others have covered the auto sorters. Here is a link the USPS addressing recommendations. They suggest the zip on the same line.
I used to install the machines that Paparmache Prince referred to back in the 90’s. I could never get the machine to read a handwritten barcode. The recognition software may have improved since then.
The machines weren’t looking in too specific a place for the zip code so if it were printed on the same line as the city/state or below it if it could read it it would sort. If not - off to the reject bin.
I meant a handwritten ZIP code.
It’s my understanding that putting a country on the bottom line increases delivery time, even if the country is good ol’ USA.
The mailpiece is sent to an outgoing international mail sorting facility (or as I and I alone call it: an OIMSF).
Postal worker checking in.
One of the key reasons a machine is faster… apart from, well being faster… is that a human operator can only sort to 50 - 75 different destinations at an old-fashioned manual sorting frame. This has nothing to do with technology and everything to do with the length of a human being’s arms. A machine has a potentially unlimited “break”, as it’s called. The upshot of this, of course, is that a manually sorted letter will need to be sorted more times. A human sorter in NYC might have a pigeon hole for California, but a machine in NYC will have pigeon holes for maybe Los Angeles, S.F., San Diego, Other (California Forward). Your letter from NYC to San Francisco will, if machine sorted and barcoded, be already in a tray marked SF before it hits the plane at JFK. When it gets to California, it’s off the plane and straight onto the relevant truck. If manually sorted, it’d be off the plane, then the tray would be opened and sorted again, and an operator would put the letter in the SF tray. This loses time.
As a manual sorter, I am expected to achieve a rate of about 1700 articles per hour, which is one every couple seconds, give or take. The MLOCRs can sort 30 000 to 40 000 articles per hour, with a staff of four (three in the US). This is more than five times faster. This efficiency is amplified when the letters arrive at the next sorting centre already barcoded, and are run through a barcode sorting machine which sorts even faster (because it doesn’t have to use OCR tech to read a typed or handwritten address as the barcode only needs to be put on once). A manual sorter at this second handling point would still be only achieving 1800 per hour or less.