I don't know if all U.S. postal service mail boxes where you drop mail in are blue across the U.S. , so sorry if I screw up the question with color.. Here in Chicago, there are mailboxes every few corners. What in the hell are those things that resemble mailboxes, but have no door to deposit mail in? They are pea soup green in my neighborhood. They look like the whole front has a door that opens with a key.. So, anyone know what those are for, or were for?