The Irish have observed March 17 as a religious holiday for more than 1,000 years. Because it falls during the Christian season of Lent, Irish families would traditionally attend church in the morning and celebrate in the afternoon. Lenten prohibitions against the consumption of meat were waived and people would dance, drink and feast on the traditional meal of Irish bacon and potatoes or cabbage.
Today, people of all backgrounds celebrate St. Patrick's Day, especially in the United States, Canada and Australia, but also in Japan, Singapore and Russia.
Until the 1970s, Irish laws mandated that pubs be closed on March 17.
The original colour associated with St. Patrick was blue, not green. The use of green began during the 1798 Irish Rebellion, when the clover (shamrock) became a symbol of nationalism and the "wearing of the green" on lapels became regular practice.