Why is there a mailbox at the end of an uninhabited 3 mile island?

[@tracyroland915]

So cool you did this video. I only know of this place because of fictious book by a popular author. One of my favorites by him. Glad to know the place is real.

[@wheelrideforbeer]

I didn't know about the book - that's interesting. Glad you watched and thanks for the comments.