St. Patrick's Day by the numbers

The National Retail Federation estimates that more than half of all Americans will join in the festivities this St. Patrick's Day—55%, to be exact. Predictably, young people lead the charge, with 72% of 18- to 34-year-olds planning to revel on March 17. About 63% of 35- to 54-year-olds will join the party, and all but 42% of those ages 55 and older will stay home.

For the more than half of America that celebrates St. Patrick's Day this year, March 17 is a big party. For the people who sell the stuff that makes a party worth attending, it's big business. The United States will spend a collective $5.9 billion on the festivities this year, a record high for all 14 years the National Retail Federation has been keeping track.

Individual spending will also hit a record this St. Patrick's Day as the average reveler will likely spend more than $40 for the first time in at least a decade. Most will spend it either making a special dinner at home or heading out to a bar or restaurant, while others will spend their $40.18 at a parade, while attending a private party, hosting one of their own, or decorating their homes or offices.

This year, countless Americans will indulge not in cabbage and corned beef, but in a different kind of delicacy derived not from Irish history, but from American fast-food culture. Each year in March, McDonald's brings back its famous Shamrock Shake, a green and minty milkshake that offers a delicious way to ring in the St. Patrick's Day season. The shake first debuted in 1970, was briefly discontinued in the 1990s, and then brought back for good when furious customers rebelled.

St. Patrick's Day isn't actually about parties or parades or even Shamrock Shakes—it's about, of course, St. Patrick. Although he was never officially canonized, St. Patrick is among the most revered of all the Catholic saints, and the feast held in honor of the Patron Saint of Ireland is the basis for the holiday. What many people don't know is that St. Patrick isn't even Irish—he was born in Roman Britain and was kidnapped into slavery by people who brought him to Ireland. He escaped to a monastery in what is now France, converted to Christianity, and in the year 432, he returned to Ireland as a missionary.

On March 17, 461, St. Patrick died at Saul, Downpatrick, Ireland as one of the most successful missionaries in history. Although he's commonly credited with driving the snakes out of Ireland, that legend is a myth. What is true, however, is that St. Patrick was instrumental in converting much of Ireland to Christianity by the time of his death.

No symbol is more closely associated with Ireland and St. Patrick's Day than the shamrock, which St. Patrick is believed to have used to explain the Holy Trinity. Four-leaf clovers were thought to be lucky since at least the Middle Ages, long before Sir John Melton made the first recorded literary reference to the luck of a four-leaf clover in 1620. There's no way to say if four-leaf clovers are actually lucky, but they are rare—just one exists for every 10,000 three-leaf clovers.

If St. Patrick's Day had an official beer, it would have to be Guinness—it is, after all, the most popular beer in Ireland. In 1759, Arthur Guinness signed a 9,000-year lease on a dilapidated property at St. James Gate in Dublin, Ireland, and began brewing ale. A decade later in 1769, six-and-a-half barrels set sail for England, the first batch ever to leave the Emerald Isle. Guinness would go onto become one of the most successful beers in the world and the one most closely associated with Ireland.

It's estimated that the world consumes 13 million pints of dark, creamy Guinness every March 17. On Oct. 16, 1801, America tasted its very first Guinness when the first eight barrels of Guinness porter to cross the Atlantic arrived in South Carolina. A man named John Heavy was the purchaser—and likely the first person ever to consume a Guinness on American soil.

A little more than 32 million Americans claim Irish ancestry. That's about 10% of the population. In 1991, Congress declared March as Irish-American Heritage Month, and by 2013, the Irish-American population in the U.S. was seven times higher than the population of Ireland.

Boston boasts the largest Irish-American population of any city in America. The #2 and #3 largest populations also belong to cities in Massachusetts, as is the city with the country's sixth-largest Irish-American population.

It is not Boston, but Chicago that lays claim to what is one of the most grandiose and famous St. Patrick's Day traditions in the world. Every year since 1962, the city has dyed the Chicago River bright green in honor of the Emerald Isle's most celebrated saint.

You might think a body of water as substantial—and not exactly clear—as the Chicago River might require more than 40 pounds of powdered dye to transform, but that's really all it takes. The powder consists of a recipe that remains a secret to this day. Oddly enough, the powder is orange before it hits the water. Protestant Irish have been known as "orange" ever since William of Orange (William III—king of England, Scotland, and Ireland) conquered the island in 1690 in a battle against Roman Catholic King James II; orange is one of the three colors on the Irish flag.

On March 17, 1732, Irishmen celebrated St. Patrick's Day on American soil for the first time in history. That soil, fittingly, was in Boston. The day was marked by the first St. Patrick's Day Parade, as well, but that parade was not officially sanctioned.

The first official St. Patrick's Day parade took place in New York City in 1762. A hundred years later in the 1860s, more than a dozen major American cities were hosting official St. Patrick's Day parades and the Irish were the largest ethnic population in New York City.

New York City hosts the largest St. Patrick's Day parade in the world: 150,000 people march in the parade, which is run entirely by volunteers who work all year to make it happen.

One very special guest stands out among the 2 million spectators who line up each year to watch the New York City St. Patrick's Day parade pass by. Timothy Cardinal Dolan, the Archbishop of New York, reviews the parade from the steps of St. Patrick's Cathedral.

When it comes to St. Patrick's Day parades, Irish-Americans beat their homeland to the punch by more than 150 years—Ireland didn't host a parade of its own until 1903. The parade was in Waterford. The capital city of Dublin wouldn't host a parade of its own until 1931.

On Dec. 20, 1891, a 17-year-old girl from Ireland's County Cork named Annie Moore left Queenstown, Ireland, for America. After spending Christmas and New Year's Eve at sea, she arrived 12 days later in New York City. She would be the first immigrant from any country to pass through Ellis Island.

The Library of Congress estimates that 4.5 million Irish arrived in America between 1820 and 1930. In the 1840s, nearly half of all immigrants were Irish—one-third between 1820 and 1860. It's important to note, however, that Irish immigrants have been in America since colonial times.

Fairly or otherwise, St. Patrick's Day is synonymous with Guinness, shots, and overflowing bars—in America, that is. From 1903 to 1970 in Ireland, however, no one had a sip on St. Patrick's Day that they didn't have to sneak. Drinking was banned, and pubs were ordered closed by the Irish government, which declared March 17 a religious holiday.

It turns out that the holiday's rep for booze-soaked debauchery is, in large part, earned. St. Patrick's Day is the #4 biggest drinking day of the year in America. New Year's Eve tops the list, with Christmas and July 4 coming in as close runners-up.

The 2019 St. Patrick's Festival in Dublin runs from March 14 through 18. When the first Dublin St. Patrick's Festival launched in 1996, however, the celebration lasted just one day and one night.

According to Discovering Ireland, there are nine Dublins in the United States—more if you count townships. Dublin, Ohio, Dublin, Calif., and Dublin., Ga., are among the best known.

The most common way to celebrate St. Patrick's Day by far is to rock the green. About 81% of Americans will wear green on March 17, a number that has changed little over the last decade. The next most common category is making a special dinner, which about 30% of the country will do this year.

The color green as a symbol of Irish nationalism can be traced to 1641 when subjugated Catholic peasants rebelled against the British crown. Oliver Cromwell eventually crushed the rebellion, which was led by a commander who rode into battle waving a green flag.

A huge wave of Irish immigrants—about 1.5 million between 1845 and 1855—fled the Emerald Isle for a new life in America in the wake of the Irish Potato Famine. Already desperately poor and suffering from cruel and suffocating oppression by the British crown, the Irish peasantry were devastated by an agricultural disease that wiped out their primary source of sustenance, the potato. Instead of coming to their rescue, the British masters of the starving Irish capitalized on their misery by waiting for them to die or flee so they could confiscate their remaining lands. Upon arriving in the U.S., the desperately poor immigrants faced new discrimination and poverty as they clung to the bottom rung of the American social and economic ladder, but a century later, one of their descendants would be elected president of the United States.

With the exception of potatoes, cabbage is more closely associated with Irish cuisine than just about any other food—and it seems that a head is in every American kitchen on St. Patrick's Day. Like the potato, cabbage entered the Irish diet out of necessity. Potatoes were the only crop that poor Irish farmers could grow enough of to survive under the tenant farming system, which since the 1600s had forced millions of poor Irish farmers to toil for British landowners in their own country. When the potato crop failed, the Irish turned to the only other readily available source of food at their disposal—cabbage.

Like all immigrants, the Irish brought with them to America their recipes and cuisine from the old country, and on St. Patrick's Day, America becomes a nation gorged on cabbage. Shipments of cabbage increase by a full 70% in the week leading up to March 17.

St. Patrick's Day is the most widely celebrated national holiday in the entire world (holidays like Christmas are not associated with individual countries). On March 17, the world goes green, and everyone gets to be Irish for a day. The reality, however, is that the festivities were exported globally not from Ireland, but from the United States. Although it's rooted in Irish legend, tradition, and religion, St. Patrick's Day as we know it is a uniquely American affair.