I like to know how things work. And in almost every case the current system for how a particular thing works evolved in stages over time from humble origins. This post covers the evolution of Mail Addresses into numbers. It turns out that every single place the United States Postal Service (USPS) is capable of delivering mail to has a specific unique number associated with it. How can that be? Well, it didn't start out that way.
The phrase "Number Please" conjures up the image of a telephone operator. Back in the day a lot of the telephone system was operated manually. An "operator" sat at an "exchange". When you wanted to make a phone call you did something (cranked on a handle in the early days) to get the operator's attention. This lit up a light on the "plug board" of the exchange. The exchange was manipulated by the operator by plugging and unplugging "patch cords". So the operator would connect herself to you, ask for the phone number you wanted to connect to, then manipulate some patch cords to connect you up.
In the very early days you could just say "connect me to Mable" and the operator knew what to do. But phones soon became so popular that asking for someone by name soon became unwieldy and everyone who had a phone was assigned a number. For a long time the "number" was a combination of letters and numbers but that was actually a con. If you look at a phone "dial" you will see that the "2" key is labeled "ABC", the "3" key is labeled "DEF", etc.
So if my phone number was "Olive 7335", which it was at one point, that really meant OL7335, "OL" being the first two letters of "Olive". And the "O" was really a "6" and the "L" was really a "5". So, for all practical purposes my phone number was 657335, a number. At some point the phone company decided that this "letters and numbers" business was not worth the bother and dropped it. People are now used to phone numbers being a series of digits.
But in an interesting development, "phone numbers" are going back to being names. Most people now use smart phones. And to call somebody they look that person up in their "Address Book" and hit the "dial" button. People only know another person's actual phone number just long enough to enter it into their address book. After that, they go by their name. (The same goes for texting, which is rapidly replacing the phone call.)
Back in the day (early '60s) there was a British TV show called "Danger Man". It was syndicated in the US under the catchy name of "Secret Agent". And for the US run, besides giving the show a new name, they slapped on a catchy new theme song. That song contained the line "they've given you a number and taken 'way your name". The USPS has given every mail delivery location a number but they haven't taken it's "address" away -- yet. But that's the end of the story. Let's go back to the beginning.
For a long time almost everybody was illiterate. Before paper was invented writing material was very expensive so most people found a way to get along without learning to read or write. Then paper was invented. This was followed by "movable type" printing. Now there was much more of an incentive to learn to read and write, and lots more people did. And if two people can read, information can be shared by one person writing a "letter" to the other person. The problem was how to get the letter from the party of the first part to the party of the second part.
Well, most of the people the typical person knew didn't live that far away. So talking a friend or acquaintance into delivering the letter worked reasonably well. But governments and some business people found it valuable to communicate over longer distances. And for a long time the "find a friend or acquaintance who is going that way" was the only option available.
Governments have the most money and the most need of long distance communications. So governments started setting up regular messenger services. Messengers would travel a fixed route on a fixed schedule carrying letters. At first these messenger services only transported "official" letters pertaining solely to government business. So business groups ended up setting up parallel messenger systems that handled commercial letters.
Eventually sanity intervened and the systems were consolidated into a single messenger system that handled both government and business correspondence. But these systems were complicated, idiosyncratic, and expensive. And most people still couldn't read or write.
Fast forward to the American Revolution and Ben Franklin. Literacy in the "colonies" was increasing and Franklin recognized that an inexpensive, simple, reliable, Mail system was valuable to everyone. So he made sure that the US Constitution (Article I, Section 8, clause 7) empowered Congress to "establish Post Offices and post Roads". The US government has been in the Post Office and Mail delivery business ever since.
One idea Franklin pushed successfully was for a standard cost to send a letter regardless of how far it was going. This drastically reduced the complexity involved in using the system. You addressed a letter. As long as you were in an area served by the USPS and you were sending a letter to a destination served by the USPS you paid the same low price ("for the low, low, cost of a stamp . . ."). This meant mail going a short distance subsidized mail going a long distance. But initially very few letters went a long distance.
Unfortunately, junk mail has changed that. We can now get bombed with catalogues, sales flyers, etc., from all over the country. And this ability to send a letter from anywhere in the country to anywhere in the country demands a uniform system for identifying where the letter is supposed to go.
And, as with the case of telephones and operators, initially whatever the system was it would be operated by people. And people are very flexible. So early on locations had what amounted to a nickname. There is the famous "Bleak House" of literature fame. The house Winston Churchill lived in most of his life was called "Chartwell".
Once you got close, people were just supposed to just know where it was. In order to facilitate the "get close" part of the process, the destination was additionally identified (in the case of Chartwell) as being near the town of Westerham in the district of Kent in the country of England. And back in the days when only rich people in fancy homes got mail that system was sufficient.
About this time a standard hierarchical form was adopted. The bottom line of the address contained the most general type of location information, typically a city, state, and perhaps a country. The next line was more specific, typically a building number and street name. And the line above was still more specific, typically the name of the recipient.
Thanks to Franklin and others, more and more people were availing themselves of the postal system. And as the number of users increased, the stateliness of the typical mail recipient's abode declined. Just going with a name like "Chartwell" stopped being tenable. So, an effort was made to give all streets in a town a unique name and each building on a given street was given a unique number.
Addresses of the form "123 Elm Street, Anytown, Anystate" came into general use. Around the World War II time period this was not always enough so large cities started getting broken up into "zones". So it became "Anytown 3" to indicate that the address was located in zone 3 of Anytown. This meant that letter sorters didn't need to be familiar with all of a large city. They just needed to know their way around whatever zone they were working in.
But by World War II mail volumes were large and a lot of the mail traveled a significant distance. By this time the USPS was organized into a hierarchy. The country was divided up into "sections". If a letter was not going to someplace local it was sent to one of a limited number of "sectional center facilities". Internally within the USPS these facilities were assigned a 3 digit number. This represents the third incursion (after street numbers and then city zones) of numbers into the business of delivering the mail.
Even after the War a lot of flexibility was permitted because the system was still a manual one, for the most part. A person can easily determine that "Wa", "Wash", and "Washington" all refer to the same state so all three forms (and several others) were permitted. And address lines that became too long were not a problem. If it looked like there would be a problem then whoever was doing the addressing would just do something like go with an abbreviation instead of spelling things out in full. The mythical "Frostbite Falls, Minnesota" worked just fine, for instance.
Then in 1963 a switch was made. The postal zones within cities were dropped. And two more digits were added to the sectional center facility number. These two extra digits allowed a specific post office within a section to be identified. And the system was publicized and given a catchy name, the "ZIP Code". People and businesses were instructed to add the ZIP Code to the city-state line. But adding the ZIP code could be a problem if the city-state line was already quite long.
So, at the same time a list of two letter state codes were promulgated and people were encouraged to use them instead of all the earlier (and usually longer) variants. So my state became "WA" and that shortening allowed the ZIP Code to fit right in.
In order to encourage the widespread adoption of ZIP codes starting in '67 bulk mailers were required to use them if they wanted to mail at a discount. So every Post Office in the country had its own unique ZIP Code. This got rid of a lot of problems caused by near-duplicate addresses. Any town could have a "123 Elm St.". And it was possible that two close together towns with similar names could have the same address. When the ZIP Code boundaries were set up the USPS made sure that each instance of "123 Elm St." (or any other specific address) ended up in a different ZIP Code.
And the 5 digit ZIP code was a big help. But there were still a lot of addresses within a single ZIP Code. So in 1983 the USPS went to a ZIP+4 system. They added a "+" and another 4 digits to the end of the ZIP Code. They also started rolling out a barcode system. All of a sudden, a bunch of ticks started appearing below the address. These ticks were designed to be read easily with a dumbed down version of the UPC Code scanners used in supermarkets.
The original barcode contained only the 5 digit ZIP code. But improvements and enhancements were added over the years. First it was expanded to include the ZIP+4 information. Finally a two digit "Delivery Point" number was added. A 5 digit ZIP Code gets us to the correct Post Office. A ZIP+4 Code gets us to the specific delivery route (or part of a route) operating out of that Post Office. The addition of the two digit "Delivery Point" number gets us to a single specific house, apartment unit, etc.
This 11 digit number (a 5 digit ZIP, plus a 4 digit +4, plus a 2 digit delivery point) gets us to a single number that uniquely identifies any specific location capable of receiving mail anywhere in the US. And in 2012 the latest version of the USPS barcode was introduced.
It is called the "Intelligent Mail" (IM) barcode and it became mandatory in 2013. It is much more elaborate than even the 11 digit barcode it replaced. The old barcode used only short ticks and tall ticks. So that each tick encoded one bit of information. The IM barcode used four tick types - short-centered, short-centered+up, short-centered+down, and long (a combination of short-centered and the "up" part and the "down" part of the other two ticks). So each tick encodes two bits of information. The IM barcode consisted of 65 ticks encoding 130 bits of information.
Ignoring some "overhead" ticks (you need to know if you are reading the barcode upside down or right side up, for instance) the "payload" translates to a 31 digit number. 11 of those digits are used to encode the ZIP+4+2 11 digit number described above that identifies the unique delivery point of the letter. Most of the rest of the digits are used to create a tracking number so letters or packages can be tracked like they can at UPS or FedEx..
The tracking number is broken into two sub-parts. The first part is the sender identification number and the second part is the item number. The USPS assigns a sender identification number to each participating company or organization. A unique item number is then assigned by the sender to each item that sender mails. Two formats are used.
Some of the "sender" numbers are short. They are assigned to (relatively) high volume mailers. There are fewer numbers but there are also fewer high volume mailers than there are (relatively) low volume mailers. By keeping the number short for some mailers there is room for a larger pool of item numbers for these mailers to use.
Other "sender" numbers are longer. This allows the system to accommodate a larger number of low volume mailers. But the trade-off is that these mailers have a smaller pool of item numbers to work with. But they shouldn't need as many as the high volume mailers so it is a good trade-off.
In either case a unique item number is assigned to each piece of mail. But the number only needs to be unique within a 90 day window. After that it can be reused. The combination of the sender identification number and the item number is a fixed size. So the combination always takes up the same amount of space within the 31 digit number.
So it is cool that the USPS can now track an item. But that's not the main point of adopting barcodes. The main point was to permit machine sorting. A mail sorting machine can sort mail by reading the barcode. It doesn't have to have the smarts to handle all the variation in regular printed addresses. And it is still legal to write an address by hand. No machine can read handwriting reliably. And they definitely can't do it at high speed.
There is a nice feature that this 11 digit unique delivery point number enables. I was sending an Amazon package to a cousin a few days ago. I filled in the address and Amazon came back with "is this the address you mean". It had made a small change to what I had entered. There are now lists available to Amazon and others of all the valid addresses in the US. Amazon chunked through the address I had provided and found no match. But it did find a very similar address, which it suggested to me.
A similar thing happened to me several months ago when I was at the USPS mailing a package. The staffer entered the address I gave and it came up "tilt". It turned out that the person who had given me the address had included a ZIP code that was completely wrong. With a little poking around the staffer was able to suggest to me a completely different ZIP code that turned out to be the correct one. That's definitely a good thing.
So is all this automation helping? I'm sure it is. But the cost of a First Class stamp has been rising quickly over the last several years. (And I'm old enough to remember when the cost of a First Class stamp went from two cents to three cents.) What's going on is that mail volume is dropping. But it costs a lot (and costs keep rising) to keep all those Post Offices running all over the place. City people like me heavily subsidize country people.
There is a high enough volume of mail to cover the overhead in cities. But that is not true in rural areas. A rural Post Office may cost less to run. But it costs a lot more on a per-letter basis to run than an urban Post Office does. The very people who benefit from this cross subsidization are the ones who scream loudest about how much it costs to keep the USPS going. But they also don't want any of those rural Post Offices, the ones that lose so much money, closed.
I know what my ZIP+4 ZIP Code is. But I don't know what my Delivery Point number is. And if there is a way to find out what it is I haven't been able to find it.. So, I only know 9 digits of the 11 digit number that represents my delivery address. Could the USPS switch over to the 11 digit number at some point? Sure. But it doesn't look like they are going to do it any time soon.
But there are lots of businesses that know what my 11 digit address is. You see many bills and pieces of junk mail come with that IM barcode printed on it. And I can tell it was printed at the same time my address was printed. It wasn't added later by the USPS. Instead, it's right there underneath the address that was printed by the people who are sending the mail to me. And you can't create an IM barcode without knowing what my particular and unique 11 digit address is.
And on an apparently unrelated but actually related subject, the decennial US Census is coming up in 2020. The Census people need to know where to look to find everyone. Well, guess what? The magic database that is used to validate addresses and to list what each address's Delivery Point is tells you almost every place to look for people.
It's not going to catch people who are living in their cars or otherwise have no fixed address. But if you regularly get junk mail then your address should be in the Delivery Point database. The Census people were able to work with bulk mailers to develop a "where to look" list when they were doing the 2010 Census and that was helpful. But this Delivery Point database business means that things have gotten much better organized since. And the Census people should be able to take advantage of that.
Giving people numbers is not just for secret agents any more.
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