This is the most comprehensive look at the entire USPS mail process that I’ve ever seen. It’s made by the Smithsonian for their National Postal Museum. The particular exhibit entitled Systems At Work is filled with amazing photos, facts, and videos about the USPS mail system.

I never really think of the United States Postal Service as a very high-tech and well-oiled machine (mainly because their local branches are anything but organized and well-run), but my goodness, their sorting facilities are on a whole different operating level. This is straight up machine porn, a whole 10 minutes of it! :)