The US Post Office has a well justified sensitivity to guns at its facilities. There have been enough shootings by postal workers in the workplace that the term "going postal" has a clear, if colloquial, definition.
So it's no surprise that the Post Office seeks to ban everyone from carrying a gun in its premises. That may be about to change. A federal judge in Denver is allowing a lawsuit challenging the gun ban to go forward. Two rural Colorado residents, who carry hand guns for self defense and with valid state concealed weapon permits, want to be able to carry their guns into the Post Office, on their person, when they pick up their mail. They don't get home delivery, and are arguing that having to leave their guns in their vehicles parked on a side street is not a reasonable restriction on their Second Amendment rights.
Well, I guess you can make an argument that you are just as likely or even more likely to encounter an armed shooter in a post office as you are wandering around generally, but this seems to be asking for trouble. Maybe the Post Office can put in a drive-by, er, drive-through window.