You probably have an inkling that modern-day mail is sorted by machines. But back in 1903, it had to be done by guys named Ralph or Wesley. They had a lot of letters to sort, and they had to do it quickly—so this is the "system" the U.S. Post Office Department came up with. (You don't have to watch the whole clip, ten seconds will give you the idea.)
Sometimes Ralph and Wes were on shift at the same time, while a third guy named Clarence kept dumping letters onto their desk:
Those things they're throwing the letters into aren't bins, but bags. Here they're tying them up, joined by Clarence as well as Samuel:
That last video was in focus enough that I became curious about those semicircular racks, which were probably made out of either iron or dinosaur bones. Alas, all I could find was a patent application for a later (1910) design that apparently improved on the design of the one we saw in the videos. Near as I can tell from the language in the application, the chief improvement seems to be that these can be broken down.
Enter a caption (optional)
In any case, the modern-day U.S. Postal Service has a decidedly more efficient system in place:
I might actually prefer to work at the older place.