Commemorating St. Patrick, the patron saint of Ireland, this national holiday has been celebrated since 461 A.D. to honor the Catholic bishop who converted the Irish to Christianity. A traditional icon, the shamrock, stems from the story of St. Patrick using the three-leafed shamrock in his sermons to represent how the Father, the Son, and the Holy Spirit -- the Trinity -- could all exist as separate elements of the same entity. His followers adopted the custom of wearing a shamrock on his feast day.

St. Patrick's Day is celebrated worldwide with pub crawls, parades and parties. It is an unpretentious, bawdy, luck-filled holiday free from the expectations of gift-giving or devout behavior.

In New York City, the annual St. Patrick's Day Parade is older the United States and has been led by the 1st Battalion of the 69th Infantry of the New York Army National Guard since 1851. Chicago also holds a large parade and dyes the Chicago River green for the holiday

Savannah, Georgia the mass at the Cathedral of St. John the Baptist followed by a raucous parade of gaudily garbed green revelers has been a tradition for nearly two centuries.