St Patrick's Day — 17 March — has grown from a quiet Irish religious feast into one of the world's most exuberant celebrations, marked with parades, green everything, and Irish culture from Dublin to Chicago. But who was St Patrick, and why 17 March? Here's the history.
See the St Patrick's Day holiday page for dates, or browse the March calendar.
When is St Patrick's Day?
St Patrick's Day is always 17 March, every year. In 2027 it falls on a Wednesday. It is a public holiday in Ireland (and in Northern Ireland and the Canadian province of Newfoundland and Labrador), and widely celebrated elsewhere without being a day off.
Who was St Patrick?
Despite being the patron saint of Ireland, Patrick wasn't Irish. He was born in Roman Britain in the late 4th century. As a teenager he was kidnapped by Irish raiders and enslaved in Ireland for six years before escaping. He later returned as a Christian missionary and spent decades spreading Christianity across Ireland.
He is traditionally said to have died on 17 March, around AD 461 — and that date became his feast day.
Why the shamrock?
Legend says St Patrick used the shamrock — a three-leaved clover — to explain the Christian Holy Trinity (Father, Son and Holy Spirit) to the Irish. The shamrock became his enduring symbol, and wearing green on the day grew from this association with Ireland, the "Emerald Isle."
(The popular story that Patrick "drove the snakes out of Ireland" is a myth — Ireland never had snakes; it's usually read as a metaphor.)
How it became a global celebration
- For centuries it was a religious feast day in Ireland, with pubs closed.
- Irish emigrants — especially to the United States — transformed it into a celebration of Irish identity. The first St Patrick's Day parade was held not in Ireland but in America in the 18th century; New York's parade is now one of the world's largest.
- Today landmarks worldwide — from the Chicago River (dyed green) to the Sydney Opera House — go green for the day.
Quick answers
Why is St Patrick's Day on March 17? It marks the traditional date of St Patrick's death, around AD 461. It became his feast day in the Christian calendar.
Who was St Patrick? A 5th-century missionary, born in Roman Britain, who was enslaved in Ireland as a youth and later returned to spread Christianity. He is the patron saint of Ireland.
Why do people wear green and shamrocks? The shamrock is linked to St Patrick explaining the Holy Trinity; green is the colour of Ireland. Both became symbols of the day.
Is St Patrick's Day a public holiday? Yes in Ireland, Northern Ireland and Newfoundland and Labrador (Canada). Elsewhere it is widely celebrated but not an official day off.