10 Surprising Facts About St. Patrick’s Day

St. Patrick’s Day on March 17 is often marked in the U.S. by quirky traditions, such as Chicago dyeing its river emerald green, but the holiday has historical and religious roots in its origin country of Ireland.

Here are 10 surprising facts you may not have known about how St. Patrick’s Day started, its legendary symbols, and how it’s still celebrated today.

St. Patrick’s Day’s namesake was not born Irish

People often wonder: “What is the true story of St. Patrick’s Day?” The holiday is named after St. Patrick, a Patron Saint of Ireland, who died around the fifth century.

However, St. Patrick is thought to have been a Roman citizen in Britain who was enslaved and taken to Ireland, either escaped or was released, then returned as a priest and converted Druids to Christianity, Marion Casey, a clinical assistant professor of Irish Studies at New York University, previously told TIME.

If you have also found yourself querying, “Why do we celebrate St. Patrick’s Day on March 17?” it’s because that is believed to be the day that he died.

St. Patrick’s Day began as a Catholic Feast Day 

If you’re ever asked, “What is St. Patrick’s Day celebrated for?” it was originally started in 1631 by the Catholic Church as a Feast Day honoring St. Patrick—one of many church holidays.

However, the holiday, imported to the U.S. by Irish immigrants, morphed into a show of Irish-American pride and worldwide celebration of Irish culture.

Legend says St. Patrick used the shamrock to teach Christianity

Legend has it that St. Patrick used the shamrock, a three-leaf clover, to teach the Christian doctrine of the Trinity—Father, Son, and Holy Spirit in one. Irish botanist and cleric Caleb Threlkeld described the connection in 1726, when he also wrote that the shamrock was the emblem of the holiday and the country’s national symbol.

However, historians say the story is likely fiction, as the plant itself is mythical and not linked to a scientific species, according to National Geographic. The shamrock became associated more broadly with Ireland as a symbol during rebellions against Britain in the 18th century.

Green became connected to St. Patrick’s Day after Irish rebellions 

Green as an Irish color has political origins. Timothy McMahon, Vice President of the American Conference for Irish Studies, previously told TIME the color dates back to the Great Irish Rebellion of 1641, where Catholic local leaders revolted against the English crown, using a green flag with a harp as an emblem.

Green was worn again during the Irish Rebellion of 1798. The Irish forces promoted the nationalistic ballad “The Wearing of the Green,” which immortalized the color’s connection with Ireland.

Before these rebellions, blue was traditionally associated with Ireland, Smithsonian Magazine reported.

The first St. Patrick’s Day parade was held in the U.S. 

The first recorded parade on the Catholic Feast Day of St. Patrick was held on March 17, 1601, in a Spanish colony in modern-day St. Augustine, Florida. More than a century later, Irish soldiers serving in the English military marched in Boston in 1737 and in New York City in 1762.

St. Patrick’s Day was promoted by the Irish government 

Inspired by Irish-Americans, Ireland’s National Agricultural and Industrial Association organized a parade in Dublin in the early 1950s to showcase Irish industry, according to the National Museum of Ireland. Dublin Tourism took over the parade from 1970, until a St. Patrick’s Day Committee was established in 1995, which grew the festival into a weekend and then a week.

The government established the weeklong St. Patrick’s Day Festival in 1995, Irish news outlet The Journal reported. The holiday was boosted that year by an Irish government campaign.

Leprechauns originated in Irish folklore  

The supernatural fairies, or sprites, were thought to bring good luck and protection to humans, or to mess up their plans. The oldest written reference to leprechauns was in a medieval story about three magical fairies, or sprites, who drug the King of Ulster into the ocean, according to National Geographic.

The legend gained popularity in the 19th century, when leprechauns were painted as grouchy shoemakers who guarded gold. Walt Disney’s depiction of a more cheerful leprechaun kicked off the current commercialized image.

“Lucky” four-leaf clovers are real—but rare

Although common three-leaf clovers are most closely associated with the saint and his holiday, much ado has been made about “lucky” four-leaf clovers. Vincent Pennetti, a doctoral student at the University of Georgia’s College of Agricultural and Environmental Sciences, told the Associated Press that it takes a recessive trait to develop a fourth leaf, so although the plants are rare, they’re real.

An American union started dyeing the Chicago River green decades ago

One of the most iconic St. Patrick’s Day celebrations in the U.S. is Chicago temporarily dyeing the river that shares its name green using about 40 pounds of environmentally friendly dye.

Starting in 1955, city workers used green dye to help identify the source of sewage in the river, NPR reported. The inspiration to dye the entire river came after Stephen Bailey, the business manager for the Chicago Journeymen Plumbers Local Union, noticed a plumber’s white overalls stained with bright green, per chicagoist. The tradition began in 1962 when the Plumbers Local Union dyed the river green with 100 pounds of dye for a week, according to Illinois’ tourism website, and continues today.

On March 16, ahead of the official St. Patrick’s Day 2024 celebrations, Chicago dyed its river emerald green as spectators looked on.

Corned beef and cabbage is an Irish-American invention 

The dish is not common in Ireland, news outlet IrishCentral reported. Instead, Irish immigrants to the U.S. reportedly found a less expensive alternative to the meat more common in their home country—bacon—in beef. They cured the beef using corn-sized crystals, hence the moniker “corned.” The beef was then paired with cabbage, one of the cheapest vegetables available. So while people in the U.S. may see corned beef and cabbage on themed St. Patrick’s Day menus, it’s highly unlikely people in Ireland will be offered the delicacy.