And while in many states (and the NYSE), it’s still referred to as Washington’s Birthday, for years before the Monday Holiday Law moved that commemoration to the third Tuesday in February, Washington’s Birthday was celebrated on February 22.
However, George Washington wasn’t actually born on February 22. Do you know when he was born?
Answer: According to the Julian calendar, which was in effect at the time, George Washington was actually born on February 11, 1731.
However, according to the Gregorian calendar, which was adopted in Britain (and its colonies) in 1752, Washington was born on February 22, 1732 (and he did celebrate his birthday on that date, after the calendar change).
You can read more about this at http://www.archives.gov/legislative/features/washington/