ZIP+4: en-dash or hyphen?
March 28, 2006 9:57 AM   Subscribe

ZIP+4: Should I use an en-dash or a hyphen wth a ZIP Code that includes all 9 digits?
posted by stopgap to Writing & Language (20 answers total)
A hyphen (phone numbers, too). You'd use an en dash in a range of numbers, like "pp. 38–55" or "1990–2000."
posted by kirkaracha at 10:02 AM on March 28, 2006

Huh. I know I've seen that phone numbers take an en dash despite not being a range. I wonder if I can find that source again.
posted by stopgap at 10:05 AM on March 28, 2006

You can see all sorts of things in this crazy mixed-up world, but if you saw that, it was wrong, and if I had seen it (in my official copyediting capacity) I would have corrected it.
posted by languagehat at 10:09 AM on March 28, 2006

I agree the hyphen is right and the en dash is wrong, but is Bartleby our only citation? I didn't see this listed in Chicago.
posted by cribcage at 10:21 AM on March 28, 2006

I hope you don't mind if I add a rider-question to this -- does anyone know what is with the usage of the nine digit these days? I've been told by my postal worker brother that the last four are for internal USPO usage and not by the general public.
posted by The Bishop of Turkey at 10:36 AM on March 28, 2006

The USPS says: "Use of the 4-digit add-on is not mandatory. ZIP+4 codes are intended for use primarily by business mailers who prepare their mail with typewritten, machine-printed, or computerized formats that can be read by the business's automated scanners during processing."
posted by smackfu at 10:40 AM on March 28, 2006

Well, even though I've done many searches for the answer to this question over the last year or so, after smackfu's comment, I went back and checked the USPS FAQ on ZIP+4. They seem to imply that either a hyphen or a dash is acceptable. They even use an en dash a couple times on that page, when the ZIP code is broken into its component parts, though never as part of a fully assembled ZIP code.
posted by stopgap at 10:49 AM on March 28, 2006

I hardly ever use the +4. For PO Boxes, it's usually redundant: If the address is "PO Box 465," the +4 will be "0465." Besides which, the mail arrives just fine without it, and I never see the +4 scribbled on in pen by some postal worker.

Having said that, occasionally I mail something with an outdated zip code — and when the clerk corrects the code, she writes all nine digits.
posted by cribcage at 10:50 AM on March 28, 2006

I went back and checked the USPS FAQ on ZIP+4. They seem to imply that either a hyphen or a dash is acceptable.

No offense to the USPS, but I don't want to live in a world where they're the ones making decisions about the proper use of en dashes.
posted by languagehat at 10:57 AM on March 28, 2006

Oh, and I don't intend ever to use those damn nine-digit codes. I dislike the five-digit ones as it is.
posted by languagehat at 10:58 AM on March 28, 2006

Technically, you don't have to use the dash at all - when it's read at all, it's read by a machine, which disregards the dash.

And on top of that, there's a two-character delivery code (keyed off the house number in the address) plus a mathematically-derived check digit - these 12 digits make up the POSTNET barcode.
posted by DandyRandy at 10:58 AM on March 28, 2006

The 9 digit code is just more specific than the 5-digit. There's probably a slight chance that using a correct 9-digit could get mail to your destination faster than just the 5-digit, but it's more likely that an incorrect 9-digit will make your mail slower than just the 5-digit. (Did that make sense?)

The big usage for 9-digit zips is for large mailers to save money by grouping their mail appropriately.
posted by inigo2 at 11:01 AM on March 28, 2006

Where is n-dash ever better than a hyphen? Is there any difference, visually? And if not, the only function for the n-dash character I can perceive is problem-causing.
posted by Rash at 11:12 AM on March 28, 2006

Where is n-dash ever better than a hyphen? Is there any difference, visually?

The en-dash is wider.
posted by kindall at 11:15 AM on March 28, 2006

I can't find anything on hyphens and ZIP Codes in the 14th edition of The Chicago Manual of Style on their online FAQs. I don't have the 15th edition yet, and you can't search inside the book at Amazon, but the Publishers Weekly review says, "Traditionalists may be bothered by the new edition's preference for ZIP Code state abbreviations." (I suspect their new recommendation will be to use postal abbeviations--CA--instead of the longer abbeviations--Calif.--though.)
posted by kirkaracha at 11:43 AM on March 28, 2006

Chicago 15 says, "The two-letter, no period state abbreviations preferred by the US Postal Service should always be used where a zip code follows, and they may appear in any context where abbreviations are appropriate. ... Many writers and editors, however, prefer the older forms..." [15.29]

And I agree. I use the older forms (Mass., Calif., etc.) — but when it's followed by a zip code, then yeah, the proper postal abbreviation would be correct. So PW can go screw. ;-)
posted by cribcage at 12:17 PM on March 28, 2006

Use of the 4-digit add-on is not mandatory.

Well, neither is the use of the zip code itself, right? My understanding has always been that zip codes are completely optional. Some friends and I once had a good time trying to obfuscate each other's addresses as much as possible, trying to see what the post office would deliver. Our small town post office was much more lenient than their Seattle post office, but zipless always got through. Their best effort to us was: "J.D. Roth, Elm, Canby, Oregon." Not bad considering there's an Elm Street and Elm Court and Elm Circle and Elm Lane and so on in town. (Canby's big on trees for street names.)
posted by jdroth at 12:24 PM on March 28, 2006

Further research indicates that the ZIP (Zone Improvement Plan) Code is mandatory on second- and third-class bulk mailers, but it seems to be optional on other stuff.

I could be wrong, though.
posted by jdroth at 12:29 PM on March 28, 2006

Seven or so years ago, I worked as the circulation manager at a newspaper with a lot of out-of-state (mail) subscriptions. The addresses wirth the zip+four actually took longer to arrive (2nd class mail) that those with only five digits. That was a while ago, of course. But unless the USPS has improved things, I'd skip the +four altogether. YMMV.
posted by wordwhiz at 3:31 PM on March 28, 2006

If there are any Processing Center employees out there, they may correct me; but as a USPS Letter Carrier, it is my understanding, as DandyRandy has pointed out, that all addresses are OCR'ed and checked against the AIMS database (a national database of addresses) and then converted into the POSTNET barcode which is sprayed onto the mail piece and read by various sorting machines. Thus ZIP's aren't really necessary with one big exception. If the address is incomplete, i.e. missing the directional indicator (NE, NW, SE, SW, etc.), the ZIP gives a BIG clue as to which part of town to sort the letter. In effect, the first 3 digits indicate the Main Post Office, the last 2 the particular Branch Post Office, and the +4 the particular street segment or section of boxes to which the letter is sorted.

Short answer - it doesn't matter which dash you use because the +4 doesn't affect anything on an individual mailing.
posted by MiamiDave at 7:44 PM on March 28, 2006

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