St Patrick's Day: 5 facts about this most Irish of celebrations

A horseshoe and clover leaf on a green wood background.
Every year, on March 17, millions of people celebrate St. Patrick's Day by wearing the color green. (Image credit: Shutterstock)

Every year on March 17, millions of people gussy themselves up in green attire, hold big parades and guzzle pints of beer, all in the name of an old Irish saint. But what's the story behind this emerald-hued holiday, and why do we celebrate it with shamrocks and alcohol? 

St. Patrick wasn't actually Irish

St. Patrick was born in Roman Britain — not Ireland — near the end of the fourth century, according to a 2006 report in the publication History Ireland. He came from a wealthy family, and although his father was a Christian deacon, historians think he didn't have a particularly religious upbringing. When he was 16, Irish raiders ransacked his family's estate, kidnapped and enslaved him, and brought him to Ireland where he worked as a shepherd. He spent six years in captivity, turning to religion for solace. It's believed that in his fear and loneliness, he began to dream of converting the Irish to Christinanity.

Patrick wrote in his spiritual autobiography "Confessio" that God's voice came to him in a dream, commanding him to escape back to Britain. There, he described having a second revelation: an angel told him to return to Ireland as a missionary. He trained to become a priest for 15 years before setting off on a dual mission to convert the Irish and minister to Christians already living there — contrary to popular belief, St. Patrick didn't introduce Christianity to Ireland. Rather than uprooting pagan Irish rituals, he incorporated them into his teachings. For instance, the Irish used to honor their gods with fire, which inspired Patrick to light bonfires to celebrate Easter. 

Patrick died on March 17, 461 A.D. (although some sources give the year 465 A.D.) which became St. Patrick's Day. 

St. Patrick's Day was originally celebrated with blue, not green

The color green has become emblematic of St. Patrick's Day, but the holiday was originally celebrated in blue. The shift to green was probably inspired by the many Irish symbols that contain green — its flag, the shamrock — as well as the island's nickname, "The Emerald Isle." People have paraded in green ribbons and shamrocks since the 17th century and Irish soldiers wore green on March 17, 1798, as a political statement during the Irish Rebellion against British Rule, Time reported. Legend has it that wearing green makes a person invisible to leprechauns that will pinch anyone they see.

In Ireland, some people still adhere to the tradition of Catholics wearing green and Protestants wearing orange on St. Patrick's Day, the colors that represent them, respectively, on the Irish flag.

Every St. Patrick's Day, the leaders of Ireland and the U.S. chitchat over shamrock

Nothing screams Irish like the simple shamrock, which comes from the Gaelic word "seamróg," meaning young clover. According to folklore, St. Patrick used the three-leaved plant to illustrate the Christian Holy Trinity in his teachings. Every year, the Irish prime minister, or taoiseach (pronounced "taysha"), presents a bowl of shamrock to the U.S. president during an audience at the White House. The tradition began in 1952, when the Irish Ambassador to the U.S. John Hearne delivered a box of clovers to President Harry Truman. 

St. Patrick's Day turns everything — even beer — green 

It's no secret that St. Patty's Day is a boozy occasion. While the Irish Guinness remains many people's drink of choice, green beer is also a favorite. The bright concoction is an American invention from 1924, which Thomas H. Curtin, a New York toastmaster and coroner's physician, is said to have served at his St. Patrick's Day bash. Green beer is simply beer mixed with green food coloring, although Curtin's recipe used "one drop of wash blue," a laundry whitener that was unfortunately poisonous to humans, according to Irish Central

The world's largest St. Patrick's Day parade is not in Ireland 

St. Patrick's Day wouldn't be complete without flamboyant parades, festivals and céilithe (pronounced "kaylee"), which are social gatherings that involve Gaelic folk music and dancing. The largest parade in the world happens every year in New York City. It was first held in 1762, 14 years before the Declaration of Independence, by a group of homesick Irish expats and soldiers who served with the British Army in the American colonies, according to the parade's website.

The world's shortest St. Patrick's Day parade is held in the Irish village of Dripsey, in County Cork, and stretches just 75 feet (23 meters) from one of the village's pubs to the other.

Tanya Lewis
Staff Writer
Tanya was a staff writer for Live Science from 2013 to 2015, covering a wide array of topics, ranging from neuroscience to robotics to strange/cute animals. She received a graduate certificate in science communication from the University of California, Santa Cruz, and a bachelor of science in biomedical engineering from Brown University. She has previously written for Science News, Wired, The Santa Cruz Sentinel, the radio show Big Picture Science and other places. Tanya has lived on a tropical island, witnessed volcanic eruptions and flown in zero gravity (without losing her lunch!). To find out what her latest project is, you can visit her website.
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