You’ve Got Mail: Sorting And The USPS

Snail mail. You may not think much of it these days, but the mail doesn’t stop and it never has. Every type of mail from postcards and letters to large envelopes and packages of all sizes moves every single day all over the US, even though it isn’t typically delivered on Sundays. Dealing with the ever-increasing volume of physical mail has called for the invention and evolution of automatic mail sorting machines that are used by both postal facilities and businesses alike.

While mail sorting machines have grown and matured over the years, the human element of the task remains intact. As long as people type addresses, write them by hand, and/or print them in handwriting fonts by the hundreds, there will need to be humans on hand to verify at least a few of them that are really hard to read.

There are roughly a dozen different types of mail sorting machines in 2023. In this series, we’re going to take a look at most of them, along with many other aspects of the United States Postal Service and its history.

Don’t Pigeon-Hole Postal Employees

Pigeon-hole message boxen at Stanford University. Image via Wikimedia Commons

As you may have guessed, mail was once sorted entirely by hand. This was accomplished using pigeon-hole message boxes — a system of cubbies, like you might see in a university office. On a larger scale, the task was broken into a hierarchy of sorting stations across the nation.

At a smaller station, a sorter might fill the cubbies based on delivery routes. Larger sorting stations had many more potential routes, so mail might be sorted by the state it is headed for, or if already there, the city. Mail would travel this system of sorting stations all the way down to the local post office, where sorters then delineate by delivery route.

This system has its limits — the sorter’s memory, for one, along with the length of their arms. It may be surprising, but that’s how it was done for much of the 20th century, until the first automated sorting machine — Transorma — was created.

Automatic for the People

While some early mechanical mail sorting equipment was realized and tested in the 1920s, the first real sorting machine was the Transorma, named so for ‘TRANsport and SORting’ plus the last names of the inventors, Marchland and Andriessen. It was built by a Dutch heavy industrial concern called Werkspoor.

The Transorma, with sorters sitting up top and bins below. Image via The Postal Museum at the Smithsonian Institute

Transorma was the first of it’s kind — a large scale, multi-position sorting machine. The point was to assign more pigeon holes per sorter by way of of mechanical switching, and end up with ultimately much larger cubbies as a result of the magic of machinery.

First, a sorter would read the address and use a keyboard to select a routing code, which was then printed in colored ink on the front. This allowed aother sorter to route it by hand later on. The machine used the typed code to program its switches, then shuffled it off to the right bin. While the Transorma could potentially have n bins, most of them had either 250 or 300. There were also single-user machines that used a different type of sorting mechanism.

How It Worked

The big Transormas were two-story affairs, with sorting stations on top and bins along the bottom. In operation, mail rode a conveyor belt from the bottom up to the sorting stations, where letters would be extracted from the belt and queued up for each sorter to add the two-digit routing code manually, by memory.

Looking down the barrel of the Transorma. Image via The Postal Museum at the Smithsonian Institute

The code was printed at 90 degrees opposite the address on the front of the envelope. The letter was then dropped through the sorting machine and onto spinning wheels that moved it along to the bin area. Then, mechanical shutters corresponding to the routing code would open, allowing the letter to fall into the correct bin. The Transorma could sort 15,000 letters per hour, which, astonishingly, is just double the rate that sorters could do it manually.

The single-user Transormas were only one floor, with the sorter sitting at one end. Once coded, the letters rode a conveyor system that ran above the bins and dropped them into the correct bins. The first and only US post office to install a Transorma opted for the 5/300 model, which means that it supported 5 sorters and 300 total bins. The machine was launched on April 10, 1957 in a post office of Silver Spring, Maryland.

But Wait, There’s More

While the story of postal automation starts with Transorma, it certainly doesn’t end there. Stay tuned for more about various types of sorting machines, automated post offices, and advancements such as ZIP codes, OCR machines, and fully automated post offices, plus a little bit of postal trivia.

52 thoughts on “You’ve Got Mail: Sorting And The USPS

  1. For what it’s worth, I’ve sent housands of small pacakges first class now ground select through the post office. With alarming regularity my packages come up missing in Detroit, Atlanta, Memphis, Nashville, and anything New Jersey in approximately this order from worst to least worst. I appreciate what gets through, but anything first class can come up missing and the post office just doesn’t care. I hope whatever technology they end up embracing improves things, but honestly I think this is as good as it’s ever gonna get.

      1. I get told to insure all the time and that prices me well out of the range of the competition. You knowingly enter into this when you deal with the post office because you have no choice. In an 11 state area SpeeDee is the best for packages. I’d like to know more about the demographics of these areas I mentioned to see if the higher theft rates can be tied in to anything ie poverty, drugs use, affirmative action hires, etc.

    1. Nice comment. I’ve been a letter carrier for 39 years, and the term “the post office just doesn’t care” is offensive to a postal employee. Most times when a piece of mail goes missing is when mailers send bulk rate mail by the thousands through our system and they don’t seal their envelopes. Then there’s the “folded” mail pieces that can easily trap a mail piece within its folds. What the general public doesn’t realize is that today’s sorting machines move so much mail in a short period of time, and some other mail is going to end up in an unsealed envelope or a folded piece of “junk mail” that most people throw out without hesitation. I know, I’ve found such pieces both in sorting at the office, and out delivering. It’s not deliberate and/or often, but it does happen occasionally. If/when we discover the mail piece, we make sure it gets to its location. The post office does care, I care

      1. > It’s not deliberate and/or often
        I don’t believe it’s deliberate, but I can say it is often. We’re out of the Atlanta distribution office, and with surprising regularity, we lose packages. They never make it out the distribution center.

      2. I mailed 2 identical Priority Mail envelopes from North Myrtle Beach. One was going to Columbia, SC, the other to Salt Lake City, Utah. Both arrived a few hours later in Columbia, SC, the SC Central Postal Center. They both arrived and left within a few minutes of each other. Guess which one was delivered first? Salt Lake City the next day. It took 4 days for the Columbia package to make it from the main post office in Columbia to it’s delivery address, a few miles away. I suspect they both went to Salt Lake City the first night. Not that the Post Office will tell you that.

      3. I’m also a letter carrier of 10 years and I care too. Most postal workers ie. Clerks, mail handlers, truck drivers, and letter carriers take pride in their work and truly care that the right mail goes to the right place at the right time. However, our management only cares about having good numbers to show their management and so on and so forth all the way up to the top. They overload our mailstream and short staff our stations. Carrier assistants are also overloaded with work in areas they are not familiar with. All of this leads to mail being misdelivered by people who are just trying to finish their impossible task assigned to each day. The whole system needs to be restructured from the TOP down.

    2. I hear ya. The theft is just rampant. For important things I just use UPS or FedEx as their insurance actually pays if something gets broken lost or stolen. I got fed up with the USPS. The problem is there is no follow through with any kind of complaint and they will purposely withhold responses for 60 days so you cant get a refund etc. I ended up filing a GAO report as so many things were being stolen, the local postmaster would not respond, and my local PO clerk told me to pound sand before telling me you can only file online. And that is a horrid experience if you are not Johnny Cochran or something. The whole service needs to be torn down and reworked imho. Their whole “Private entity with Federal protection” has gotten them this far into the dumpster fire. They continue to hike rates the average us citizen has to pay while giving businesses and bulk services lower rates which is extremely shitty to the taxpayer. Add to that the layers of mismanagement and tenured employees that dont give a shit and that has many red flags of a company I dont want to do business with as a taxpayer or corporation. You should also be able to call someone an asshole when they are being an asshole to you at the desk without threat of federal prosecution. If you can tell I have had a bellyful of the USPS and their employees at most of the levels I have had the displeasure of dealing with. The PO in my mom’s small town is amazing and friendly and helpful but even they finally got my mom to stop sending checks through the mail as they said it is just too rampant at this point. Then there was them getting into bed with satan and giving amazon that cherry deal that we subsidize that they couldn’t even handle properly to the point that amazon has all but taken delivery back they sucked so bad. Yep focused on a whole fleet of vehicles and chained distribution centers because the usps cant get paper mail across town in less than 3 days. Then you also had sample pak mail that we subsidized as well when they finally caught on to uncle chang receiving container loads of “personal mail” in the early oughts. Ugh it is really amazing anyone gets anything. I don’t know the solution other than letting MikePostalServiceLLC which has all the same rights to deliver the mail as their private, federally funded service, give them some competition while taking the load off like ups and fedex currently are. Hopefully MikePostal will actually have decent employees and secure drop points, and ffs insurance that pays you if they mess up. Guaranteed delivery dates with a refund per day it is off at least, and all mail delivered by 11am like Royal so you can actually respond to mail and do business in a timely fashion and things arent constantly a day or three behind. Actually hire the number of workers required to get the job done safely and less gruntled and not farm out hiring to some low budget bootstrap temp agency. Those would certainly perk up my ears. Otherwise we have to just disguise all goods and checks as junkmail or dental tooth whitening ads as those seem unaffected by the thefts lol. Best of luck. I know I will probably get poked for going on a rant but just so incredibly fed up with them losing breaking stealing things I have actually insured and being flatly refused without further explanation, or just being swept along until the time limit passes. There is no recourse because no one is in charge of them….

        1. it is tax payer funded on some level. the land and construction of the bldg. the LE operations that are conducted through the agency. The government contributions to the health insurance and retirement for the employees

      1. For the record, I don’t think its the fault of the grunt-level postage employees when post goes missing. As someone who used to mail defective shipments (and receive defective shipments that were supposed to be sellable product), average people are generally terrible at packaging (yes, even with ~expensive~ overpriced consumer electronics!!!). Blaming a post worker for a system that is, understandably, in dire need of an overhaul is like blaming a McDonald’s worker for their food tasting too fast.

  2. OK, this article was confusing so I checked the wikipedia page. *Two* of these machines were installed in the US, one in Maryland as described and one in Rhode Island. However they were in use around the world since being invented in the Netherlands in 1927.

    As is typical, the US was a laggard in using technology installed abroad (*cough* mobile phones, electronic banking, cotton spinning…). Took 30 years for the first installation and by then computerization was already being developed, so these didn’t last long.

  3. Junk mail keeps the system alive, kill that and goodbye snail. At some time there will be a fusion of commercial delivery and USPS. They already deliver for that other company on Sunday. I remember printed color markings at right angles on envelopes received, I wonder when that stopped.

  4. USPS is dreadful and unapologetic when they truly screw-up on a grand scale. In a period of two months earlier this year, I experienced two horrific incidents. First, was to return from vacation after twelve days of my mail being on a vacation hold at my local P.O. to discover for no explanation whatsoever my carrier took it upon himself to return all my mail to sender. Never, obviously, was one piece retrieved and returned. The task of doing that mine! Was an experience I wouldn’t wish on anyone! Second incident, was having seen on my Informed Delivery that I was to receive four pieces of mail one of which was a government check, the other three were nondescript pieces. Those arrived but not the government check! I’ve had contact with the USPS Office of the Inspector General, useless and frustrating and unconscionable that the check hadn’t been located and it’s now almost two months and I still do not have the missing item l
    USPS should truly be under investigation for these type of happenings and others for sure!

    1. Horrific indeed. Have the check issuer cancel the check and reissue it. Better still, upgrade your banking system to 20th century standards and start doing things online.

      1. Unfortunately, my garage door installer wants a check or cash. Since I use online banking and never use checks I have a cashier’s check being mailed to me because I don’t want to use an ATM to withdraw $2K+ in cash.

        1. It doesn’t matter whether you withdraw $2K+ or $2 from an ATM. As long as the American banking systems insists on using the magnetic strip instead of the chip, skimmers can copy your card.

          “American” also includes countries like Mexico, a favorite vacation spot form some. Expect that at least 50% of all ATM you’ll encounter in Mexico are fake or “enhanced” ATMs. The service persons get bribed, or extorted (cheaper!), to install the copying hardware directly into the machines. Sometimes it’s easy to spot such “enhanced” ATMs (some have have an active Bluetooth transmitter). But I’m not convinced that carrying a bag of cash into Mexico is that smart either…

          Funny thing is that, just a few decades ago, it was normal to pay for a car in cash. Seems we feel less safe nowadays…

  5. I rather like the US post office. They’re cheaper than the other major carriers, and they’ve been quite reliable and on-time for me. I’m looking forward to the rest of this series!

    There was an string of incidents 15 years ago where the postie would deliver our envelopes to our neighbor, but that stopped. I assume a different postie took over our route. Other than that, they’ve worked well for me.

    They are operating under some rough constraints though in terms of budgeting and what services they are allowed to provide. The fact that the system works at its present scale given all the rubbish that gets imposed on them impresses me, and I do wish they were allowed to do more. I would like to see some form of postal banking come back – there’s not enough bank service out in the boonies.

    1. I like the Post Office too.

      A story — in the 70s as a teenager, we set forth on a prank. Sent a letter to my girlfriend across town. I addressed it something like this …

      Can’t remember the address. But it’s the house near the cul-de-sac with two planters in the front windows. Not the house with planters and a brown porch. The street is 3rd from the left off of Main street by the new hotel. Turn right on that street.

      It was well-received and delivered. And, there were some scribbled notes and a big ! as if to say Eureka. Gotta think that postie had fun that day.

      1. I remember reading a story like that, except it was a young child writing a letter to their grandmother. The ‘address’ provided was similarly a detailed description of grandma’s house, and the local post office did a bit of detective work to find the correct house. Institutional knowledge, I suppose?

  6. For regular mail and sending post cards USPS is passable. But after having miserable problems with having packages sent to me via USPS, anything in order I pick private carrier even if I have to pay significantly more. Specifically the online and package tracking is a joke. Says out for delivery then shows up a county or two over the next day. If delivered at all, delivered several days later. If lost, no one on phone to talk to and no ability to just go pick it up myself at an office. List goes on.
    That said, my postal carrier is awesome and friendly and works hard. Not sure at what level the disconnect happens but the post office itself is always full of people, “customers” and employees alike in zero hurry to actually get anything done. Everyone is rude… somewhat understandable but not at all acceptable for a civil society.
    Now to send stuff I go to the indie operated FedEx or UPS stores. Worth the very small increase cost just in my time alone. In and out 5 minutes tops, professionally and with tracking that works and insurance that I have never even needed.

  7. I have had a package go trhru the USPS just to be misdelivered here at my local post office. This has happdropened multiple times. I Made the mistake of complaining. I did get a postal official of some kind call me and try to tell me it was my fault. I told her I was the addressee. She then said that mail sometimes drops of the conveyor. I then asked if it was picked up. She then hung up. When I have something come through the USPS I hold my breath praying I will get it. I trust them about as far as I can throw them.

    1. Well, I had a different story. I went to the P.O. about misdelivered mail. Long story short when I ordered was being given the tracking numbers for packages being shipped to random addresses in my town. Legitimate packages addressed to other people. Someone must have cracked the code for the tracking system. (I had the employee look up the tracking, when she stepped away and I could see on the screen a box number at the UPS store. Then the UPS store said the package was legit addressed to their customer and their customer came to pick it up. Not USPS fault at all, some high level scam.). Happened at least once more to me as well.

  8. As a tech for the P.O. I highly recommend sealing your letters with scotch tape. Never use dollar store stickers to seal it they fall off all the time. Also how many letters just are not sealed at all. The sticky flaps get ripped off and contents fall out. Also never mail coins, pens or thumb drives in envelopes. Letters go through tight turns between metal rollers and also sometimes through want is called switchback units to get mail all facing the same way. It reverses so fast you can’t even really see it with naked eye. So letter reverses but contents “coins” don’t they just rip through the letter wall. Imagine being in your car driving at a 100 mph and reversing immediately at a 100 mph. You would fly through your window. Every morning I find thumb drives and other assorted small objects in our machines. One last thing don’t put glitter on your envelopes they just make a mess and also interfere with cameras and sensors.

    1. I recommend using cardstock to keep the envelope inflated and filling the envelope with glitter.

      When it runs through the machine rollers the glitter will be blown out of the envelope and get into the machines sensors.

      Hours of fun for the P.O. tech!

      To be really nasty, add a plastic bag full of glue.

  9. Oddly enough my local P.O. in rural NorCal has gone to a seeming quiet every other day service. Some weeks I only see them alternating days, and then they’ll deliver on a Sunday. Its Bizarre to say the least. Makes sense, and I too would do it randomly and unannounced so people just get used to it. I haven’t got the pattern entirely worked out, if there is one.

  10. It’s okay to share your opinions and experiences with the USPS,
    But, let’s not forget the story.
    I look forward to more of the articles in this series.

  11. I have been having problems getting packages delivered on the weekends. For the past several weeks, I have had no mail delivered on Saturday, instead I get it on Sunday. I talked to some of my neighbors, and they agreed with me.

    I track my packages, so that I know when they are out for delivery. Lately I haven’t been getting an out for delivery message. There are times, especially on Friday or Saturday, that I wait until after 9pm for packages that never come.

    One time I called USPS Customer Service because I never received a package. I was told it states delivered at front door or near mail box, so as far as we are concerned you received your package. Thank goodness I have a great relationship with the company that sent the package to me.

    Another time the supervisor at my local post office said why are you upset, it is insured. I told him that I wanted my order. It was a big sale, and there is no guarantee that I could gets the items again, and definitely not at the sale price .

    Recently, my family signed up and paid for a class in advance (no refunds if cancelled within 24 hours). Since I didn’t expect a package, and it was a Saturday, we all went to the class. Several hours later I checked my messages, and saw that a package was delivered. There was nothing I could do at that moment. When we arrived home, I went to a neighbor and asked her if she had the package. Nada! I checked the company’s site, and there was a message stating it was left with an individual. Who??? Not anyone in my household. We were in a class during the time stated. So I sent an e-mail to my contact in the company to let them know that no one in my household had the package. I am glad that I have a good relationship with this company for 5 years. This is also the company that the supervisor made a remark about insurance. I had to wait until Monday to contact USPS Customer Service, where I explained that no one in my household could have possibly received this package. If I had to go to court, I could prove where we were. Late that day I received an e-mail from the supervisor that he was going to investigate it. I waited until Friday to contact him regarding any updates, and if he talked to his employee to see if they could remember if it was a woman, man, teenager or child, and the race if the person. I live in a metropolitan city, and our street is very diversified with many ethnicities. I received his reply that the package was found and out for delivery. Sitting on the front steps with one of my daughters and a neighbor, the postal truck pulled up and had a package for my daughter, but not my missing one. I waited until 9:15pm to send another E-mail to the supervisor telling hime I did not get the package and to please redeliver it on Monday. The next day (Saturday) I thought about it, and sent him another E-mail asking him to send it back to the sender. I also “cc” the company on this E-mail. Then I sent an E-mail to the company’s contact person, explaining why I did it. Monday, I received text messages that I had 2 new packages out for delivery. Well the missing package was delivered, but the other ones wasn’t. After waiting past 9pm. I received messages that I could pick my packages you at the post office. My daughter also received the same message. Today is Thursday, my daughter and I did some early errands. I saw the mail carrier up the street so we decided to sit outside to see if she had mail for us. She did. We went in and out of the house several times, and rested a bit before heading to the post office. Needless to say, when we got to the post office we were told our packages at been delivered at our mail box. The time state was not correct…between sitting outside and going in and out several times, we would have seen them. If course the supervisor, that I have been in contact with, was not there. Having asthma and walking several miles round trip in the heat, I was pissed off. We we got home, our packages were there. Nothing like playing head games! I called the post office several times to let them know, but no one answered. Also my daughter gave them her phone number to call her…no call back either.

    1. I think you may know that packages and mail can be delivered by different vehicles at different times. Its down to volume. One handles easily delivered mail and one is doing just packages.

  12. United States Postal or the postal office they have management issue until they fix the management issue they just going to keep running the hamster wheels eventually United States Postal it’s going to be something in history forgotten and no longer exist I see it I see it coming soon ..

  13. Take it from a mail carrier. The problem isn’t us. it is all the way up at the top . Postmaster general. Management cares More about having impressive numbers and as little overtime as possible than they care about getting the right piece to the right place on time. Maybe your local PO had 8 call ins because they work their employees into the ground.

    1. My oldest brother was a small town Postmaster,
      his supervisor harassed him so much about productivity.
      He died of a heart attack, alone, one afternoon in his Post Office.
      Fifty one years old.

  14. I am a retired postal employee, carrier and clerk. The problem exists not the employees that actually do the work but Management. It’s true all they are concerned with is the numbers. The packages have increased greatly but the employees have not. The employees that have been in there are all retiring. Getting older not old. The new employees are just coming in off the street, they no longer have to take tests as we use to. Very few stay, most leave after a day, some never come back from lunch at orientation. I can say the few older employees that are still there do care, but get bogged down with more work because there is no one else there. The call in rate is high because of overwork. The employees that have years invested care about their customers and try to do everything they can for you. It’s management and not highering quality employees. This workforce is a mess. We used to be able to give extra service as a carrier but they now time every little thing, so you can’t give personal service as we use to. Every thing is being taken away even in other business. Look after covid more do not wish to work, the employers were begging for anyone to work. This is whats happening now in the Post Office. Now as far as mailing letter and card size, please make sure you tape the seal, you know those little corners at the top where it doesn’t stick tape it there also. If you mail pictures, put a name and address on it. If you mail cash in a card, list the amount on the inside of card, with a name and address. This is so we can get it back to you. The envelopes, depending on the kind do not hold up. As mentioned earlier about the machines. If you mail invitation cards such as wedding, please add the extra postage or take to the PO to have weighed and postage applied otherwise you may see them all come back for postage. Save time and a headache for you. If you wish to mail something bulky, extra postage most likely will be required. When Christmas come PLEASE do not use thin rice paper type envelopes,, they do not hold up.. Also tape the back if you think it isn’t sealed to hold uo in the mail.. Now I know alot of you say privatize. Well it may or may not be such a great answer. Do you realize we do not charge extra for the change of address, or forwarding your mail. We are suppose to deliver to each household everyday, regardless of weather. You are vrequired to keep your sidewalks free of snow and ice. Also I am adding keep your yard tools and hoses so they are not a tripping hazard. Most Postal employees really care about their jobs and giving you quality service when able. There are alot of Postal Employee out here working to give you the best they can. Thanks for your time in reading this.

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