I walked to the corner today to drop something in the mailbox and... it was gone. I've passed the same corner a couple of times in the past week, but I wasn't heading for the box either time so I didn't notice it was gone. I don't know when this happened; it probably could have been any time within the past three weeks.
If I have something I need to mail I usually leave it for our carrier, but if I miss the delivery the mail got picked up from the box around 1 pm. The city has been replacing sections of sidewalk in areas around the city this spring, and it's possible the box was removed in preparation for that.
Meanwhile I did determine that there is a box a block further north, on the other side of the main road where I wait for the bus, and a few streets beyond that one there's another that has a 5 pm pickup, where I ended up walking to deposit my mail today.