this summer, the american postal workers union filed a complaint against the us. postal service about the agency’s plans to dismantle 671 mail sorting machines at facilities across the country. Although some of these machines are typically replaced each year due to wear and tear, this mass removal would involve a significant percentage of the more than 8,500 pieces of automated processing equipment used by the USPS across the country.
The move also coincided with new USPS cost-cutting measures, instituted by Louis DeJoy, a former Republican party fundraiser whom President Donald Trump appointed Postmaster General earlier this year, to which which is blamed for late deliveries and delays in the mail. The situation, which comes just before a general election in which coronavirus precautions will lead many Americans to vote by mail, could affect the outcome: The USPS has announced that it may not be able to deliver mail-in ballots to voters on time if requested no later than 15 days before the election.
Automated machines, like the ones being decommissioned, greatly speed up the mail sorting process for the USPS, which delivers what amounts to roughly half the world’s mail. His equipment can seal and sort up to tens of thousands of pieces of mail per hour, performing what is “essentially a mechanized, automated version of the same process that was done in the 19th century,” says Daniel Piazza, chief curator at the Smithsonian Postal Museum. National Institution in Washington, D.C. Of course, this process goes much faster than when a sorter was “a person standing in front of a huge wall of cubicles, reading the address and putting it in the right box for the right city,” he adds. scientific american spoke with piazza about how mail sorting machines work and why they’re so crucial to today’s postal service.
[an edited transcript of the interview follows.]What are the automated processes that a letter goes through in the current mail system?
The first stage is something called acceptance: the process in which the postal service takes possession of your mail and enters it into the system. you can leave a letter in a corner mailbox, take it to the counter [to] give it to a clerk, or leave it in your own mailbox for the carrier. or a large postal company could take a tractor-trailer to a large bulk sorting and distribution center.
The next step, usually, is for [the mail] to go through “cancelling machines,” which bring the letter in, orient it the right way, and check the postage. The machine’s cameras can read labels (phosphorescent or ultraviolet ink that is incorporated into US postage stamps) under ultraviolet light and know that there is postage on your letter. and then cancel the [stamp] and apply the postmark. cancellation is what erases the postage stamp so that it cannot be used again; [is replaced with a] postmark that has information such as the place and date of mailing. if there is no postage on the letter, it will be ejected from the machine for someone to review. but those cases are quite rare.
once the mail has been cancelled, it goes to the sorting part of the machine. the optical character reader will read the address and spray a barcode on the front of the piece of mail indicating [where it should go]. most people don’t realize that their actual zip code is, I think, up to 17 or 19 digits now. there’s the five or maybe nine digit zip code that you put on the envelope, but that barcode that’s sprayed on the envelope contains about 17 or 19 digits that encode the mail, at least to your block and sometimes to your house. all of that can be put on planes or trucks and shipped from the sorting and distribution center to the local post office for delivery.
When the letter arrives at the local processing and distribution center, it is put into machines that now sort the mail, not by city or ZIP code, but by the carrier’s actual route within the city. in many cases, it is pre-set in what is known as walk order, the order in which the carrier is going to walk the route. And that automates every other process: Carriers used to have to get to the post office, I’d say five or six in the morning, and do all that sorting of mail for their route before they went to deliver the mail. now [when] they arrive in the morning, the mail is already delivered from the distribution center to the local post office, sorted in that walking order.
When did the postal service start relying on these machines?
The first part of the mail processing workflow to be automated was the postmarking of postage stamps, which had been done almost exclusively by hand until the early 20th century. but that still required one person to handle each piece of mail: orienting it the right way to get through the canceling machines, making sure the stamp is in the top right corner, and so on. it remained almost entirely manual until the late 1950s; in a sense, we figured out how to sort mail and put a man in space at about the same time. The Transforma machine that was introduced in 1957, and the multi-position letter sorting machines that were introduced a little later, were still based on the model of a human operator sitting in a chair. these were essentially conveyor belts or other mechanisms that would put a piece of mail in front of that operator. the operator would read the address and, through a few keystrokes, encrypt that mail to its destination. and then the machine would take that mail and deposit it in the appropriate container.
then you have the introduction of optical character recognition, [or ocr], which can actually read handwritten and typed addresses. much of that technology was developed in the 1960s and early 1970s by private industry, but under contract to the postal service. this technology is on your computer today. When you scan documents, letters, or a book and then tell Adobe Acrobat or whatever program you’re using to do OCR, that software you’re using on your computer is directly related to these postal contracts and their postal applications. As accurate as OCR is and as much as it has progressed in the last 50 or 60 years, there is still a certain percentage of mail that machines cannot read. maybe something is obscuring the address, or the handwriting is particularly bad. in those cases, those letters are still read and reviewed by a human operator. but nowadays a lot of that is done remotely, [in] what’s called a remote coding center. mail sorting teams across the country transmit images of the mail they can’t read to this handful of remote encoding centers.
and then move on to the situation we have today, which is: there are now huge machines that can do all of this in one process. they can organize all the pieces of mail in the same address, cancel the mail, read the address and sort it to its destination. most of the mail that goes through the mail system is not even actually seen or handled, during the processing phase, by a human employee.
When did machines begin to sort packages and letters?
The machining of packages was a separate and much more complicated process, from a mechanical and engineering point of view, due to the enormous variety of sizes and dimensions of the packages that are handled through the mail. what has happened over time is that the volume of postal mail, or first-class mail, has decreased tremendously. and the volume of packaged mail has increased tremendously, especially in the last three to five months, with covid-19 and more people indoors and ordering things that come in small packages.