1792    The Postal Service Act, establishing the United States Post Office Department, is signed by President George Washington.

1959    The {{USS|Barbero|SS-317|6}} and United States Postal Service attempt the delivery of mail via Missile Mail.

1963    ZIP Codes are introduced for United States mail.

1986    In Edmond, Oklahoma, U.S. Postal employee Patrick Sherrill guns down 14 of his co-workers and then commits suicide.

1991    In Royal Oak, Michigan, a fired United States Postal Service employee goes on a shooting rampage, killing four and wounding five before committing suicide.