# ZIP codes
**URL:** https://boards.straightdope.com/t/zip-codes/812342
**Category:** Cecil's Columns/Staff Reports
**Created:** [April 13, 2018, 9:33am UTC](https://boards.straightdope.com/t/zip-codes/812342 "2018-04-13T09:33:57Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@Musicat](https://boards.straightdope.com/u/Musicat)
#### Post date: [April 13, 2018, 9:33am UTC](https://boards.straightdope.com/t/zip-codes/812342/1 "2018-04-13T09:33:57Z")
With reference to the latest Cecil Column, [Where did two-letter postal abbrevs. come from,](https://www.straightdope.com/columns/read/9694/where-did-two-letter-postal-abbreviations-come-from/) I’d like to expand on this a bit, as I worked on mailing & shipping software, including barcoding, in the last century.
While ZIP+4 digits are the only ones printed as text, a barcode may include 2 more, called [Delivery Point.](https://en.wikipedia.org/wiki/Delivery_point) Cecil mentioned this briefly as 11 digits, but in more detail, the DP numbers actually drill down to a single address. In typical residential addressing, this means the last 2 digits of the street number, i.e., if your address is 1234 Fake Street, your ZIP+4 will have “34” appended. Since the +4 digits define one side of one block, adding DP means each address in the country can be defined with 11 digits. (There are exceptions.)
The neat thing about the 2-character state abbreviations is that it is possible, without too extreme alphabetic manipulations, to define each of the 50 states, 4 territories (and a few more, if needed) with only 2 distinct letters. Remember that this was devised in a day when everything was being computerized, but computers were weaklings compared to now; every digit was valuable and required expensive data storage space, so programmers tried mightily to conserve. Also, computers work better with fixed data fields, and allowing a fixed number of characters rather than a variable amount simplifies and speeds up processing.
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### Author:  [@DesertDog](https://boards.straightdope.com/u/DesertDog)
#### Post date: [April 13, 2018, 11:17am UTC](https://boards.straightdope.com/t/zip-codes/812342/2 "2018-04-13T11:17:30Z")
> [@The Perfect Master](#):
>
> The report also suggests avenues for future growth — notably linking ZIPs with geocoding (latitude and longitude coordinates), to make delivery routes yet more efficient and facilitate better communication with people in high-risk areas like flood or wildfire zones.
There already is a system in place that can specify any spot in the world to a 3-meter square with a [three-word code](https://what3words.com/about/), words because they’re easier to remember than a string of digits. For example, there is a [locomotive](https://www.google.com/maps/@33.4176095,-111.8191203,77m/data=!3m1!1e3?hl=en&authuser=0) on display at a park near where I live. The front end is _info.courtyard.moats_ while the back end is _miracle.brushing.vest_. There are currently 14 language sets so you could for example, find your location in English and have it pronounceable for your friend in Berlin.
I think it is way ahead of whatever the USPS has on tap.
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### Author:  [@tafinucane](https://boards.straightdope.com/u/tafinucane)
#### Post date: [April 13, 2018, 3:41pm UTC](https://boards.straightdope.com/t/zip-codes/812342/3 "2018-04-13T15:41:24Z")
> [@DesertDog](#):
>
> There already is a system in place that can specify any spot in the world to a 3-meter square
> …
> I think it is way ahead of whatever the USPS has on tap.
The zip codes are not geographic regions, they are portions of a postal route. Cecil vaguely alludes to this when talking about the zip+4. The codes only exist as a collection of mail boxes. This is unfortunate, because organizations use zip codes as a proxy for geolocation for things like, billing, insurance rates, emergency services, etc.
A concrete example I’m familiar with is sports media rights. Usually teams’ broadcast regions are defined by zip codes, and the building that the TV cable is hooked up to will correspond to a mail box. Now that this content is consumed on people’s phones, the rights holders want the same fine-grained control, but it breaks when a consumer is watching the game from the middle of a lake.
Various organizations maintain their own map of geolocation to zip code, but the post office wisely suggests they should provide such a map themselves.
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### Author:  [@PetroDude](https://boards.straightdope.com/u/PetroDude)
#### Post date: [April 13, 2018, 3:42pm UTC](https://boards.straightdope.com/t/zip-codes/812342/4 "2018-04-13T15:42:13Z")
For me, you can’t mention the process of abbreviating the state names without mentioning Gary Gulman.
[Mildly NSFW](https://www.youtube.com/watch?v=ocjTsBH_nYM)
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### Author:  [@Powers](https://boards.straightdope.com/u/Powers)
#### Post date: [April 13, 2018, 3:49pm UTC](https://boards.straightdope.com/t/zip-codes/812342/5 "2018-04-13T15:49:54Z")
> [@DesertDog](#):
>
> I think it is way ahead of whatever the USPS has on tap.
That’s debatable. The what3words system is a) proprietary, b) language-dependent, c) not easily machine-readable/codable, and d) completely without geographic correlation. The fact that the two ends of your locomotive have completely different encodings is often considered a bug, not a feature.
Powers &8^]
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### Author:  [@El\_Zagna](https://boards.straightdope.com/u/El_Zagna)
#### Post date: [April 13, 2018, 6:03pm UTC](https://boards.straightdope.com/t/zip-codes/812342/6 "2018-04-13T18:03:51Z")
Somewhere in the recesses of my memory is a story about a fad in the early days of the postal system where people would try to come up with cryptic addresses to see if the post office could figure it out. The only one I remember was something like this:
Hill
James
Street
Mass
Which translated to:
James Overstreet
Underhill, Massachusetts
It was delivered correctly.
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### Author:  [@Saltire](https://boards.straightdope.com/u/Saltire)
#### Post date: [April 13, 2018, 6:40pm UTC](https://boards.straightdope.com/t/zip-codes/812342/7 "2018-04-13T18:40:22Z")
> [@Musicat](#):
>
> The neat thing about the 2-character state abbreviations is that it is possible, without too extreme alphabetic manipulations, to define each of the 50 states, 4 territories (and a few more, if needed) with only 2 distinct letters.
Not to mention all the provinces and territories of Canada. Do Mexican states have 2-letter abbreviations? Are they all distinct from the US and Canadian ones?
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### Author:  [@Sunspace](https://boards.straightdope.com/u/Sunspace)
#### Post date: [April 13, 2018, 7:39pm UTC](https://boards.straightdope.com/t/zip-codes/812342/8 "2018-04-13T19:39:06Z")
> [@Saltire](#):
>
> Not to mention all the provinces and territories of Canada. Do Mexican states have 2-letter abbreviations? Are they all distinct from the US and Canadian ones?
The Canadian codes do not overlap with the US ones, but I believe the Mexican ones do (BC = British Columbia and Baja California; MI = Michigan and Michoacán).
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### Author:  [@El\_Zagna](https://boards.straightdope.com/u/El_Zagna)
#### Post date: [April 13, 2018, 9:35pm UTC](https://boards.straightdope.com/t/zip-codes/812342/9 "2018-04-13T21:35:23Z")
I guess BJ for Baja California was too… juvenile.
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### Author:  [@Sunspace](https://boards.straightdope.com/u/Sunspace)
#### Post date: [April 13, 2018, 10:00pm UTC](https://boards.straightdope.com/t/zip-codes/812342/10 "2018-04-13T22:00:00Z")
> [@El\_Zagna](#):
>
> I guess BJ for Baja California was too… juvenile.
Baja California Sur is BS… 🙂
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### Author:  [@Musicat](https://boards.straightdope.com/u/Musicat)
#### Post date: [April 14, 2018, 12:37am UTC](https://boards.straightdope.com/t/zip-codes/812342/11 "2018-04-14T00:37:15Z")
> [@tafinucane](#):
>
> The zip codes are not geographic regions, they are portions of a postal route. Cecil vaguely alludes to this when talking about the zip+4. The codes only exist as a collection of mail boxes. This is unfortunate, because organizations use zip codes as a proxy for geolocation for things like, billing, insurance rates, emergency services, etc.
Which causes many problems in large rural areas, not so much in concentrated urban areas. I used to live in a dense LA neighborhood with cookie-cutter type houses and the real estate value range was quite narrow; one ZIP code covered only a few blocks.
In my rural neighborhood now we have multi-million dollar coastal properties and broken-down shacks in the same ZIP. Zillow’s “average price” numbers are laughingly out of whack with reality and quite useless.
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### Author:  [@dtilque](https://boards.straightdope.com/u/dtilque)
#### Post date: [April 14, 2018, 4:03am UTC](https://boards.straightdope.com/t/zip-codes/812342/12 "2018-04-14T04:03:24Z")
> [@Musicat](#):
>
> The neat thing about the 2-character state abbreviations is that it is possible, without too extreme alphabetic manipulations, to define each of the 50 states, 4 territories (and a few more, if needed) with only 2 distinct letters.
Actually there are more than 4 territories: DC, PR, VI, AS, GU, MP and then three more for Pacific countries that the USPS delivers for: MH, FM, PW. But considering there’s 676 two-letter combinations, there’s plenty of room for more.
> [@](#):
>
> Remember that this was devised in a day when everything was being computerized, but computers were weaklings compared to now; every digit was valuable and required expensive data storage space, so programmers tried mightily to conserve. Also, computers work better with fixed data fields, and allowing a fixed number of characters rather than a variable amount simplifies and speeds up processing.
Until I read Cecil’s column, I thought computers were the reason for only two letters. Consider that in 1963, if you had any kind of sizeable file, say a customer address file, it would be stored on mag tape. Mag tape drives were horribly slow and increasing each record by even a single letter would significantly increase processing time for all kinds of programs.
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### Author:  [@mamafrogger](https://boards.straightdope.com/u/mamafrogger)
#### Post date: [April 14, 2018, 4:28am UTC](https://boards.straightdope.com/t/zip-codes/812342/13 "2018-04-14T04:28:26Z")
I live in a city with twelve letters and a space, Oklahoma City, and have simply abbreviated it as OKC many times over the years. Everything has gotten where I sent it so the PO must approve it. Certainly much easier to type.
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### Author:  [@DesertDog](https://boards.straightdope.com/u/DesertDog)
#### Post date: [April 14, 2018, 4:52am UTC](https://boards.straightdope.com/t/zip-codes/812342/14 "2018-04-14T04:52:06Z")
> [@Powers](#):
>
> That’s debatable. The what3words system is a) proprietary, b) language-dependent, c) not easily machine-readable/codable, and d) completely without geographic correlation. The fact that the two ends of your locomotive have completely different encodings is often considered a bug, not a feature.
Yes, it is proprietary because it was made by a company, not a government agency. People can use it for free.
It _is_ language dependent – in fourteen of them so far. The 3-word code for a particular location can be received in one language then be expressed in the 3-word code for another by selecting it in a drop down menu.
I would assume the word codes have a numeric equivalent that can be sent from machine to machine when us pesky humans are not involved. If not, there’s always OCR.
I have no idea what you mean by “without geographic correlation.” A particular code points to a particular point on the earth. That can be translated to a LatLong if you like, as shown in their [video](https://youtu.be/JTy7C47I8w0?t=60) or the other way around.
The 3-meter granularity would, say, enable me to guide a friend to where I am in a [crowd](https://az616578.vo.msecnd.net/files/2016/03/10/635932304424008629424413315_crowds.jpg) watching a parade. If that same granularity confuses you because one end of a locomotive has a different code than the other, I guess you could call that a bug.
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### Author:  [@dtilque](https://boards.straightdope.com/u/dtilque)
#### Post date: [April 14, 2018, 4:55am UTC](https://boards.straightdope.com/t/zip-codes/812342/15 "2018-04-14T04:55:08Z")
> [@mamafrogger](#):
>
> I live in a city with twelve letters and a space, Oklahoma City, and have simply abbreviated it as OKC many times over the years. Everything has gotten where I sent it so the PO must approve it. Certainly much easier to type.
If you use the correct zip code, the name of the city is irrelevant. They only use it if there’s an error in the zip code and they have to figure out where you really intended to send the letter. How do they know there’s an error in the zip? It could be it’s an unassigned zip code. Or if it is assigned, it’s very likely that the post office for that zip code does not have the street address in its delivery area.
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### Author:  [@CBEscapee](https://boards.straightdope.com/u/CBEscapee)
#### Post date: [April 14, 2018, 12:52pm UTC](https://boards.straightdope.com/t/zip-codes/812342/16 "2018-04-14T12:52:17Z")
> [@Sunspace](#):
>
> The Canadian codes do not overlap with the US ones, but I believe the Mexican ones do (BC = British Columbia and Baja California; MI = Michigan and Michoacán).
Baja California and Nuevo Leon are the only ones using just 2 letters. The others all have 3 or more.
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [April 14, 2018, 12:59pm UTC](https://boards.straightdope.com/t/zip-codes/812342/17 "2018-04-14T12:59:43Z")
> [@](#):
>
> Quoth **DesertDog** :
>
> I have no idea what you mean by “without geographic correlation.” A particular code points to a particular point on the earth. That can be translated to a LatLong if you like, as shown in their video or the other way around.
An example of geographic correlation would be if points next to each other had two of their three words the same. Well, usually, at least; you’d inevitably have some points where you have the equivalent of 12:59:59 rolling over to 1:00:00, where everything changed.
If I tell you two addresses with the same 5-digit ZIP code, you can tell that they’re fairly close together. If I tell you two addresses with the first four digits the same, you don’t know as much, but it’s a good chance that they’re in the same metropolitan area. Even if I only tell you the first digit or two, you can narrow it down to a general region of the country.
Or consider latitude and longitude. I can specify a location on the Earth with as much precision as I like, by giving more digits after the decimal point. But even if I just tell you that I’m at 40ish north by 80ish west, you have some idea of where I am. And with a little spherical trig, if you give me the coordinates between two points on the Earth, I can tell you exactly how far apart they are, to within as much precision as you gave me the points. But with the three-word system, it’s not meaningful to say “I’m somewhere in the info.courtyard area”.
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### Author:  [@eastcheap](https://boards.straightdope.com/u/eastcheap)
#### Post date: [April 14, 2018, 5:33pm UTC](https://boards.straightdope.com/t/zip-codes/812342/18 "2018-04-14T17:33:23Z")
> [@Musicat](#):
>
> Which causes many problems in large rural areas
In my case, the nearest post office is five miles away but my post office (and ZIP code) is ten miles away in another county.
So, for geolocation purposes, I’ve ended up memorizing five ZIP codes for different situations: my own (by far the least useful), the nearest town’s, representative codes for the two nearest cities, and a code for the nearest major metropolitan area. None of which gets you anywhere near my home, of course.
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### Author:  [@ftg](https://boards.straightdope.com/u/ftg)
#### Post date: [April 14, 2018, 7:12pm UTC](https://boards.straightdope.com/t/zip-codes/812342/19 "2018-04-14T19:12:47Z")
> [@El\_Zagna](#):
>
> Somewhere in the recesses of my memory is a story about a fad in the early days of the postal system where people would try to come up with cryptic addresses to see if the post office could figure it out. The only one I remember was something like this:
>
> Hill
> James
> Street
> Mass
>
> Which translated to:
> James Overstreet
> Underhill, Massachusetts
>
> It was delivered correctly.
The version I saw as a kid:
Wood
John
Maine
John Underwood, Andover Maine.
Likely UL.
---
### Author:  [@Melbourne](https://boards.straightdope.com/u/Melbourne)
#### Post date: [April 14, 2018, 10:44pm UTC](https://boards.straightdope.com/t/zip-codes/812342/20 "2018-04-14T22:44:35Z")
> [@dtilque](#):
>
> Actually there are more than 4 territories: DC, PR, VI, AS, GU, MP and then three more for Pacific countries that the USPS delivers for: MH, FM, PW. But considering there’s 676 two-letter combinations, there’s plenty of room for more.
>
> Until I read Cecil’s column, I thought computers were the reason for only two letters. Consider that in 1963, if you had any kind of sizeable file, say a customer address file, it would be stored on mag tape. Mag tape drives were horribly slow and increasing each record by even a single letter would significantly increase processing time for all kinds of programs.
In 1963, a lot of stuff was still on paper tape and punch cards (‘do not mutilate spindle of fold’).
And on paper: a piece of furniture you seldom see today is the fan-fold binder storage rack.
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