Americans celebrate George Washington's birthday, along with Abraham Lincoln's, on "President's Day." "President's Day," however, is observed the Monday before Washington's actual day of birth.
It has been so long since George Washington was alive, how do we really know when he was born? It isn't as easy to figure out as you might think, especially since Washington was born 20 years before the introduction of the calendar that we use today. Fortunately, someone left a clue inside a letter.