And sometimes an address that references a box number is both the "where they get mail" and the "where they live" address. I grew up at the address of "Route 1

And sometimes an address that references a box number is both the "where they get mail" and the "where they live" address. I grew up at the address of "Route 1, Box 78, City, State ZIP". That was the rural mail delivery route, but it was the only actual address there was, unless you wanted "last house on county road 601 before you go over the top of the mountain" sorts of things. (The mailbox in question was on a post at the end of our driveway, and said "78" on it.) UPS and FedEx would deliver there, though sometimes we had to point out to a new UPS driver that no, we weren't box 79; they were two miles away on the next bit of the mail route. This also points out the changeability of addresses. Before I was old enough to remember, it was Route 1 Box 150A. And then ten or fifteen years ago, they went through and named all the streets and numbered all the houses, so it became "420 Streetname, City, State ZIP". The postman still knew that when my grandfather sent mail to Box 150A it should come to us, though. My current house is a duplex. The normal scheme would be something like "100 Streetname, unit A" or something, but somehow we ended up with "100A Streetname" instead. For added confusion, the actual doors aren't labeled, just the mailboxes.