• Similar to Mardi Gras, St. Patrick's Day was originally a religious holiday.
• St. Patrick's Day is named for St. Patrick, the Patron Saint of Ireland.
• Born in the 4th century A.D., St. Patrick was a Roman-British missionary to Ireland.  Not much is known about the work he did during his lifetime, however, he became the Patron Saint of Ireland by the 9th century A.D.
• St. Patrick was originally associated with the color blue.  However, the change to green began in the 1700s as the holiday came to be associated with Ireland as a whole, and not just St. Patrick.
• The significance of the Shamrock is that St. Patrick supposedly used it to explain the Holy Trinity to the pagans of pre-Christian Ireland.
• Since the feast day of St. Patrick falls during Lent, a local bishop has to lift the ban on eating meat for the one day that St. Patrick's Day is celebrated.
• In 1780, George Washington grants the Continental Army a holiday, "as an act of solidarity with the Irish in their fight for independence."
• The longest-running St. Patrick's Day celebration in the United States is in Boston, which has held festivities since 1737.

Have any obscure St. Patrick's Day facts or traditions that I may have missed?  Share them in the comments!