The Post Office must mechanize because, if the mail volume continues to grow, it would be impossible to cope with the great flood of mail within a relatively few years, using present-day methods.
—Postmaster General Arthur E. Summerfield, 1957

Behind the Scenes

The Multi-Position Letter Sorting Machine (MPLSM)
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A short, silent film showing the Multi-Position Letter Sorting Machine (MPLSM).
© Copyright United States Postal Service. All rights reserved.

[silent video]

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Employees hard at work at the stations of a Multi-Position Letter Sorting Machine.

Codes and machines revolutionized the Postal Office in the 1960s. The ever-growing volume of mail drove the Post Office to introduce ZIP Codes. Machines began taking on more and more of the work of moving the mail. Postal workers using these machines could sort 30,000 letters an hour.

Since then, the pace and scale of automation in the postal system has exploded.

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Letter carrier collecting mail from mailbox.

“Dear Congressman Smith”
From Long Island to Capitol Hill

American citizens conduct the everyday politics of the nation through the mail, in letters like this from Joe Jones in Long Island, New York, to his congressman in Washington.

Mr. Jones drops his letter in a familiar collection box, a postal worker picks up the mail, and then this piece begins to follow a new path through the system.

At the processing center in Hicksville, NY, the letter is run through a facer-canceller. By 1968, dozens of processing centers around the country had these new machines. They oriented the letters face-up, in the same direction, so the machine could cancel each stamp—automating two jobs that postal workers had done by hand for more than a century.

Mr. Jones’s letter joins hundreds of thousands of others flowing through a new Multi-Position Letter Sorting Machine (MPLSM) at the Hicksville center. Twelve postal workers sit at stations around the machine. The machine moves Mr. Jones’s letter into position in front of one of the operators, and he or she types in part of the ZIP Code for the Washington, D.C., area. The machine sorts the letter to join others headed for Washington. Within a second, the next letter takes its place.

With thousands of others, the letter is poured into a mail sack and loaded onto a train for Washington.

At the Washington Post Office, mail clerks at a second MPLSM sorts the letter for the unique ZIP Code of the U.S. Congress.

The letters delivered to the Congressional mailroom. In the mailroom, a postal worker sorts it into the boxes for congressman, and a messenger delivers it to his office. A member of the congressman’s staff reads the letter and writes a response for the congressman’s signature.

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Employees working at stations of a MPLSM machine.
River of Mail
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River of Mail is a nine-minute video produced by the Post Office Department in the late 1960s to teach the public about mail processing methods used during the 1960s and early 1970s.
© Copyright United States Postal Service. All rights reserved.

Letters of greeting,

letters of pleading,

letters of gossip,

of friendship, of love.

Checks for purchase,

checks for payment,

checks for deposit to account,

checks for just about any amount.

Advertisements from the stores,

hometown papers with all the scores,

manuscripts, postscripts, notes, codes,

thousands of votes, millions of quotes.

We are the writing-est people in the history of mankind,

well over 80 billion pieces of mail a year.

And each year, up three billion or so.

A surging river of mail.

The mid century challenge of the Postal Department:

find modern ways to help move the mail.

Move swiftly into the present, mechanize, computerize, modernize.

The time for the new is now.

Mail is vital. Everyone must help.

Those who manufacture, those who trade, those who sell, those who buy,

insurance, banking, and stock market men, letter writers all.

Of each ten letters, eight are for business;

eighty percent is business mail.

Office buildings are factories where the product is mail.

Improve the service and everyone gains.

The post office and business working together can overcome problems

of high-rise proportions.

Mail rooms for buildings, machinery to speed the internal flow.

From city to city

to town and village,

crossing the continent on pavement and rail,

the river of mail is the economy's life blood.

If it'd stop flowing, so would prosperity.

Mail began flying over 50 years ago.

We've come a long way from Jenny to jet.

First Class today gets first-class service.

All Priority Mail that's going long distance now travels by air.

Hundreds of small towns get this new service.

From feeder lines and charter planes.

With the mail flights come added passenger flights.

That independent spirit the man on the street can help too,

mailing early in the day, using ZIP Codes on all his mail.

Taking advantage of innovations like self-service postal units

open 24 hours a day.

For the Service man overseas, there's nothing quite equal to a letter from home.

Wherever he is, the mail follows.

The distance adds importance and meaning,

bridging that distance with the finest mail service ever, is a big job for both the Post Office and the Military.

To keep the precious postal link unbroken,

means planning for new techniques and modern machines to handle the flood.

Machines that can stack, can cancel and sort.

Machines that can read more swift than the eye.

Giant computers that will measure, record, and predict.

New tools, new ideas.

A new postal service for the future.

Man and machine, commerce, industry, and government, the postal employee and you,

working together, can bring change.

And change is coming, to cope with the flow.

Omaha & Ogden RMS duplex handstamp
MPLSM keyboard
Multi-Position Letter Sorting Machine Keyboard

Systems at Work