The postal service did not require city dwellers to have mailboxes at their homes until 1916. Before that, carriers would deliver the mail to the door, ringing the bell twice to signal that the mail was there, or knocking.
The Postman Always Rang Twice
The postman always rings twice.
Have you ever wondered where that phrase came from?
For decades after home mail delivery began, this was true because letter carriers handed mail over in person.
The typical doorbell signal was two rings.
Of course some homes didn't have doorbells.
Carriers got tired of knocking so they carried wooden knockers like this one.
But efficiency experts determined that two hours were being lost each day while postman waited for patrons.
So in 1916, the post office mandated mailboxes or mail slots for all homes.