# Why use City, State, and Zip Code on envelopes? **URL:** \ **Category:** Factual Questions\ **Created:** [March 27, 2013, 7:12pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125 "2013-03-27T19:12:18Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![whc.03grady](https://avatars.discourse-cdn.com/v4/letter/w/a6a055/32.png) [@whc.03grady](https://boards.straightdope.com/u/whc.03grady)\ **Post date:** [March 27, 2013, 7:12pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/1 "2013-03-27T19:12:18Z")
A zip code encodes the city and state. Isn’t it redundant to have to include the city and state when addressing an envelope? “59711” _means_ Anaconda MT (yes, it actually means a particular _post office_ in Anaconda MT; the distinction isn’t important for this question); so why are we to address an envelope, essentially John Doe 401 Main Anaconda MT Anaconda MT ? ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [March 27, 2013, 7:20pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/2 "2013-03-27T19:20:00Z")
because if a digit of the zip code gets unreadable the address no longer functions. redundancy is good. ---
**Author:** ![Terra1041](https://avatars.discourse-cdn.com/v4/letter/t/c5a1d2/32.png) [@Terra1041](https://boards.straightdope.com/u/Terra1041)\ **Post date:** [March 27, 2013, 7:20pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/3 "2013-03-27T19:20:18Z")
I believe it’s a redundancy check of sorts. If you make a mistake in the ZIP, like 57911 instead of 59711, they can check it against the city to see what you really meant. ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [March 27, 2013, 7:22pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/4 "2013-03-27T19:22:36Z")
It’s for redundancy. It’s for redundancy. ---
**Author:** ![Lukeinva](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lukeinva/32/17872_2.png) [@Lukeinva](https://boards.straightdope.com/u/Lukeinva)\ **Post date:** [March 27, 2013, 7:23pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/5 "2013-03-27T19:23:19Z")
You’re right the zip code does denote the town, city, village, etc. Whatever. However, once it arrives do you expect the clerks to look up which street the O’Grady’s live on? No. They sort by street (perhaps more than one street) and then by house number. There are many postmen in the town where I live and they each have their own route. In days past you could address a letter: O’Grady, City. But it was then up to you go to the post office and ask for any mail. ---
**Author:** ![cjepson](https://avatars.discourse-cdn.com/v4/letter/c/a9adbd/32.png) [@cjepson](https://boards.straightdope.com/u/cjepson)\ **Post date:** [March 27, 2013, 7:28pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/6 "2013-03-27T19:28:43Z")
> [@Earl\_Snake-Hips\_Tucker](#): > > It’s for redundancy. > It’s for redundancy. I think it’s for redundancy. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [March 27, 2013, 7:30pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/7 "2013-03-27T19:30:30Z")
why is O’Grady getting John Doe’s mail? ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 27, 2013, 7:30pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/8 "2013-03-27T19:30:40Z")
From what I’ve seen, one ZIP code can encompass multiple towns, and one city can be divided into many ZIP codes. So you really do need both the city and the ZIP code to nail it down. My own city (Ann Arbor) has several ZIP codes. I’ve shipped packages all over the country via FedEx. When preparing a shipping label on their website, they make you enter the ZIP code before the city. Sometimes the web page fills in the city once you’ve entered the ZIP code, but sometimes there will be a short list of cities to choose from, all of which are associated with that ZIP code. ---
**Author:** ![leahcim](https://avatars.discourse-cdn.com/v4/letter/l/b4bc9f/32.png) [@leahcim](https://boards.straightdope.com/u/leahcim)\ **Post date:** [March 27, 2013, 7:31pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/9 "2013-03-27T19:31:41Z")
I always just put latitude and longitude down to the hundredth of an arc second on my addresses and let the PO sort it out. Once you have that, everything else is redundant info. ---
**Author:** ![TimeWinder](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@TimeWinder](https://boards.straightdope.com/u/TimeWinder)\ **Post date:** [March 27, 2013, 7:33pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/10 "2013-03-27T19:33:53Z")
> [@Lukeinva](#): > > You’re right the zip code does denote the town, city, village, etc. Whatever. However, once it arrives do you expect the clerks to look up which street the O’Grady’s live on? The OP was only talking about city and state. Street and house number aren’t encoded in the Zip, although Zip+4 might get close. Think: Hex Ample 123 Dolly Drive 55057 Assuming everything’s clear, I’d guess that would get a letter delivered just fine. ---
**Author:** ![Lukeinva](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lukeinva/32/17872_2.png) [@Lukeinva](https://boards.straightdope.com/u/Lukeinva)\ **Post date:** [March 27, 2013, 7:38pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/11 "2013-03-27T19:38:44Z")
> [@Lukeinva](#): > > You’re right the zip code does denote the town, city, village, etc. Whatever. However, once it arrives do you expect the clerks to look up which street the O’Grady’s live on? > > No. They sort by street (perhaps more than one street) and then by house number. There are many postmen in the town where I live and they each have their own route. > > In days past you could address a letter: O’Grady, City. But it was then up to you go to the post office and ask for any mail. > [@TimeWinder](#): > > The OP was only talking about city and state. Street and house number aren’t encoded in the Zip, although Zip+4 might get close. Think: > > Hex Ample > 123 Dolly Drive > 55057 > > Assuming everything’s clear, I’d guess that would get a letter delivered just fine. Woops! I did misread the OP. In your example above I have received mail addressed just like that. ---
**Author:** ![Elmer\_J.Fudd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/elmer_j.fudd/32/1211_2.png) [@Elmer\_J.Fudd](https://boards.straightdope.com/u/Elmer_J.Fudd)\ **Post date:** [March 27, 2013, 7:42pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/12 "2013-03-27T19:42:50Z")
Zip codes do change and Aunt Mabel ain’t likely to know that when she sends you her annual fruit cake. But the biggest reason is that about one in fifty addresses have an error in the zip code (I ship about 500 packages a week and a bad zip code is an almost daily occurrence - luckily our shipping software red flags most of these errors, but only because it has city and state to match against.) ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 27, 2013, 7:49pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/13 "2013-03-27T19:49:18Z")
> [@TimeWinder](#): > > The OP was only talking about city and state. Street and house number aren’t encoded in the Zip, although Zip+4 might get close. Think: > > Hex Ample > 123 Dolly Drive > 55057 > > Assuming everything’s clear, I’d guess that would get a letter delivered just fine. It may or may not. If Hex Ample lives on Main Street, and three or four podunk towns share the 55057 ZIP code - each with its own Main Street - then there could be three or four different places where that letter might end up. ---
**Author:** ![Lord\_Feldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lord_feldon/32/341_2.png) [@Lord\_Feldon](https://boards.straightdope.com/u/Lord_Feldon)\ **Post date:** [March 27, 2013, 8:35pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/14 "2013-03-27T20:35:35Z")
> [@Machine\_Elf](#): > > It may or may not. If Hex Ample lives on Main Street, and three or four podunk towns share the 55057 ZIP code - each with its own Main Street - then there could be three or four different places where that letter might end up. But the city name wouldn’t help since it’s valid for the entire ZIP code. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 27, 2013, 8:56pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/15 "2013-03-27T20:56:07Z")
> [@Lord\_Feldon](#): > > But the city name wouldn’t help since it’s valid for the entire ZIP code. 😕 If there are four Main Streets in that ZIP code - one in each of the four towns in that ZIP code - then yes, the city name really will pin down which of the four main streets the letter should go to. In this situation - multiple cities in one ZIP code - you could conceivably leave the ZIP code off, but you could not leave the city off and just hope that your letter arrives at the correct Main Street. Although you could leave off the ZIP code in that particular situation (multiple cities in one ZIP code), you can’t do it all the time, because some cities are sprawled out over multiple ZIP codes. ---
**Author:** ![Peanuthead](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peanuthead/32/360_2.png) [@Peanuthead](https://boards.straightdope.com/u/Peanuthead)\ **Post date:** [March 27, 2013, 8:57pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/16 "2013-03-27T20:57:59Z")
I’m pretty sure the Zip Code +4 will narrow down a location to a specific address. If it is a private house you might not even need a name. Try sending yourself an envelope with nothing but the zip+4 and see what happens. ---
**Author:** ![kaylasdad99](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kaylasdad99/32/3398_2.png) [@kaylasdad99](https://boards.straightdope.com/u/kaylasdad99)\ **Post date:** [March 27, 2013, 9:05pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/17 "2013-03-27T21:05:03Z")
> [@TimeWinder](#): > > The OP was only talking about city and state. Street and house number aren’t encoded in the Zip, although Zip+4 might get close. It gets _damned_ close. My apartment complex has 26 sets of four townhouse/garden apartments, designated in an alphanumeric code of A-N (such as S-3 or A2) When I looked up my ZIP+4 (on google), it gave me both my apartment, and the one next door. ---
**Author:** ![RaftPeople](https://avatars.discourse-cdn.com/v4/letter/r/6f9a4e/32.png) [@RaftPeople](https://boards.straightdope.com/u/RaftPeople)\ **Post date:** [March 27, 2013, 9:06pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/18 "2013-03-27T21:06:18Z")
Just a guess, but it’s probably due to ZIP codes being introduced fairly recently, the format had already been established (in addition to the various ambiguities that do arise with zip alone) ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [March 27, 2013, 9:13pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/19 "2013-03-27T21:13:18Z")
> [@kaylasdad99](#): > > It gets _damned_ close. My apartment complex has 26 sets of four townhouse/garden apartments, designated in an alphanumeric code of A-N (such as S-3 or A2) When I looked up my ZIP+4 (on google), it gave me both my apartment, and the one next door. Yeah, it’s really close. The last two (real) digits of the bar code (in order, zip, +4, delivery point, check digit) are your actual box. The postal barcode is 11 digits (actually 12, since there’s a check digit), but that’s the [old bar code (short and long bars)](http://en.wikipedia.org/wiki/POSTNET). The new bar code [(IMB)](http://en.wikipedia.org/wiki/Intelligent_Mail_barcode) uses four bars, and contains much more information. ---
**Author:** ![Lord\_Feldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lord_feldon/32/341_2.png) [@Lord\_Feldon](https://boards.straightdope.com/u/Lord_Feldon)\ **Post date:** [March 27, 2013, 9:14pm UTC](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125/20 "2013-03-27T21:14:12Z")
> [@Machine\_Elf](#): > > If there are four Main Streets in that ZIP code - one in each of the four towns in that ZIP code - then yes, the city name really will pin down which of the four main streets the letter should go to. In this situation - multiple cities in one ZIP code - you could conceivably leave the ZIP code off, but you could not leave the city off and just hope that your letter arrives at the correct Main Street. Place names are for entire ZIP codes, not subdivisions of ZIP codes. [Next page](https://boards.straightdope.com/t/why-use-city-state-and-zip-code-on-envelopes/654125.md?page=2)