Once upon a time, mail would get to the right town with just a zip code. Once there, it was up to the local office to figure out exactly where the address was. These days, 99% of US mail is sorted successfully by machine with optical readers. But if your handwriting is so bad that the machines can't decipher it, or if the envelope got wet and the ink ran, it will be sent to the Remote Encoding Center in Salt Lake City, Utah. Or rather, a picture of it will be sent there. At this level of sorting, a combination of human and computer power will use a strange but effective system of comparison to figure out where that mail is supposed to go. If they can't do it, the last resort is completely human before the postal service gives up and returns it. Tom Scott give us a look inside the Remote Encoding Center to see how it's done.