New York City’s General Post Office unfurls its grand white facade along two full blocks between Thirty-first and Thirty-third Streets on Eighth Avenue. It’s open around the clock all year long (as midnight draws nigh on April 15, representatives of the Maalox and Excedrin concerns pass out free samples to harried taxpayers in the tall marble hall), so at any hour a passer-by may drop in and poke into the alcoves where displays of mail pouches and old photographs and engravings tell the history of the New York postal service.

These exhibits are Joe Cohen’s doing. He is the curator of the post-office museum and the unofficial historian of the Postal Service when he’s not busy with his regular duties as general supervisor of platform operations—”plus,” he adds with weary pride, “about fourteen other jobs.”

This October afternoon he is not at the General Post Office, but one block south and one over, on Ninth Avenue, at the Morgan Delivery Facility. The Morgan isn’t anywhere near so spectacular as its full-blown counterpart, although it does have uncommonly handsome elevator doors, gleaming bronze with cast panels showing various ways the mails have traveled from the days of the pony express to the era of biplanes that were drafted into service during the Army’s unhappy stint flying airmail. Joe Cohen is proud of those doors, but he’s just as pleased with the bit of post-office history that is clattering away vigorously at his elbow.

It is a canceling machine, the Flier, made by the International Postal Supply Company of Brooklyn in 1905 and still pulling its weight. Mail processor/machine operator Hugo Chamorro stands feeding it envelopes. Each time he does, a short, wide conveyor belt moves the piece of mail into the half-dozen steel rollers that send it whipping beneath the die that stamps the date on it. The two-foot ride takes far less time to occur than it does to read about.

“Depending on the operator,” says Pete Santana, who has charge of the floor during the noon-to-eight tour, “it can handle as many as ten thousand letters an hour.” Santana came on the job in 1952, eight years earlier than Joe Cohen—the Morgan seems full of lively veterans—and at that time the dies were changed every hour so that the mail would arrive at its destination bearing the information that it had gone into the Flier between 4:00 and 5:00 P.M. or between 9:00 and 10:00; today this has been scaled back to P.M. and “minus P.M. ”

“There were thirty Fliers on the floor when I got here,” says Santana, “and they’d do about a half-million a day. My first job was to run up and down the aisles checking the counters that keep track of how much mail passed through.”

Today the remaining Fliers are reserved for outsized and oddly shaped letters. The rest of the mail—the surge, as it’s rather poetically known by the postal workers—comes slapping and rustling in a steady freshet through the big M-36s—spectacular machines that read the phosphorus that coats every stamp, then flip the letter around into the proper position for canceling just about as fast as the eye can follow.

This is the slow time on the floor—“You ought to be here about five,” says Cohen; “that’s when things are cooking”—but all around there is the sense of the tidal flow of immense amounts of mail. The nation may be drifting toward illiteracy, but you’d never think it to watch the torrent of written communications being bagged and unbagged, canceled and sent down long conveyor belts to be broadcast to the corners of the world.

Cohen nods toward the nearest M-36. “We can handle up to seven million pieces in a day.”

Every piece of Manhattan’s mail posted west of Fifth Avenue and north of Fourteenth Street moves through this room—enough to keep seven of the veteran Fliers working. They stand in a battery, their trays covered with an impasto of decals cautioning safety, and only the manufacturer’s name on their bases giving an indication that some are older than others. On the earlier models the legend curls about with an exuberance reminiscent of the last century; on the later machines it is severe and linear. But the mechanism is identical.

They are simple, sturdy machines, nowhere near as impressive as the M-36s or the wonderfully elaborate pneumatic system that once sent tubes holding five hundred pieces of mail shuttling back and forth beneath the city, and even arcing like artillery shells across the bridge into Brooklyn. But Cohen is fond of the Fliers. With the billions of pieces of mail they have handled in their long working lives, they hold up remarkably well on the daily cleaning that is pretty much all the maintenance they require. Are there any plans to replace the Fliers? Santana shakes his head. “The fact is, they’ve never have been able to improve on these.”