Before you don your "Kiss me, I'm Irish" tee and set out to find a perfect pour of Guinness (or four), read up on some history of the day where we all claim to be at least a wee bit Irish.

1. We should really be wearing blue on St. Patrick's Day.

Vintage St. Patrick's Day postcard.
A vintage St. Patrick's Day postcard.

Saint Patrick himself would have to deal with pinching on his feast day. Though we've come to associate kelly green with the Irish and the holiday, the 5th-century saint's official color was "Saint Patrick's blue," a light shade of sky blue. The color green only became associated with the big day after it was linked to the Irish independence movement in the late 18th century.

2. St. Patrick wasn't Irish.

St. Patrick's Grave, Down Cathedral
The burial place of Saint Patrick outside Ireland's Down Cathedral.
Central Press/Getty Images

Although he made his mark by introducing Christianity to Ireland in the year 432, Patrick wasn't Irish himself. He was born to Roman parents in Scotland or Wales in the late 4th century.

3. St. Patrick's Day used to be a dry holiday.

A 1952 Guinness ad.
Guinness is an inseparable part of the modern St. Patrick's Day tradition.
Picture Post/Hulton Archive/Getty Images

As you might expect, St. Patrick's Day is a huge deal in his old stomping grounds. It's a national holiday in both Ireland and Northern Ireland, but up until the 1970s, pubs were closed on that day. (The one exception went to beer vendors at the big national dog show, which was always held on St. Patrick's Day.) Before that time, the saint's feast day was considered a more solemn, strictly religious occasion. Now, the country welcomes hordes of green-clad tourists for parades, drinks, and perhaps the reciting of a few limericks.

4. New York City's St. Patrick's Day parade has been happening since 1762.

St. Patrick's Day parade in New York City, 1960
A picture of New York City's St. Patrick's Day parade, circa 1960.
Peter Keegan/Getty Images

New York City's St. Patrick's Day Parade is one of the world's largest parades. Since 1762, roughly 250,000 marchers have traipsed up 5th Avenue on foot—the parade still doesn't allow floats, cars, or other modern trappings. Cardinal Timothy Dolan, the Archbishop of New York; and Miracle on 34th Street actress Maureen O'Hara have served as Grand Marshal.

5. Chicago literally runs green for St. Patrick's Day.

Green Chicago River on St. Patrick's Day
Every year, the Chicago River is dyed green for the holiday.
Tasos Katopodis/Getty Images

New York may have more manpower, but Chicago has a spectacle all its own. The city has been celebrating St. Patrick by dumping green dye into the Chicago River since 1962. And though the organizers won't reveal their exact formula, we do know that the orange powder used is dispersed through flour sifters by the local Plumbers Union.

6. For some St. Patrick's Day parades, it's the thought that counts.

Vintage St. Patrick's Day postcard.
A vintage St. Patrick's Day postcard.

Not every city goes all-out in its celebratory efforts. From 1999 to 2007, the Irish village of Dripsey proudly touted that it hosted the Shortest Saint Patrick's Day Parade in the World. The route ran for 26 yards between two pubs. Today, Hot Springs, Arkansas, claims the title for brevity—a mere 98 feet.

7. There's a reason for the shamrocks.

Vintage St. Patrick's Day postcard.
This postcard was printed circa 1910.
The Casas-Rodríguez Postcard Collection, Flickr // CC BY-NC-ND 2.0

How did the shamrock become associated with St. Patrick? According to Irish legend, the saint used the three-leafed plant (which is not to be confused with the four-leaf clover) as a metaphor for the Holy Trinity when he was first introducing Christianity to Ireland.

8. Cold weather helped St. Patrick's claim to fame.

Vintage postcard of St. Patrick.
An illustration of Saint Patrick and the snakes that probably never existed.

In Irish lore, St. Patrick gets credit for driving all the snakes out of Ireland. Modern scientists suggest that the job might not have been too hard—according to the fossil record, Ireland has never been home to any snakes. Through the Ice Age, Ireland was too cold to host any reptiles, and the surrounding seas have staved off serpentine invaders ever since. Modern scholars think the "snakes" St. Patrick drove away were likely metaphorical.

9. There's no corn in that beef.

Plate of corned beef and cabbage.
A plate of corned beef (which has zilch to do with corn) and cabbage.
bhofack2/iStock via Getty Images Plus

Corned beef and cabbage, which has become a St. Patrick's Day staple for Irish Americans, doesn't have anything to do with the grain corn. Instead, it's a nod to the large grains of salt that were historically used to cure meats, which were also known as "corns."

10. Americans run up quite a bar tab on St. Patrick's Day.

Vintage St. Patrick's Day postcard.
After that much Guinness, you'd be forgiven for doing a little dancing.

It's estimated that 13 million pints of Guinness will be consumed worldwide on St. Patrick's Day, and in America, overall beer sales will be up 174 percent. In fact, it's the biggest day for bars in the country. And in general, it's expected that Americans will spend over $6 billion celebrating the holiday come March 17.

11. It could have been Saint Maewyn's Day.

Vintage
Vintage "Erin Go Bragh" postcard.
antifixus21, Flickr // CC BY-NC-ND 2.0

According to Irish legend, St. Patrick wasn't originally called Patrick. His birth name was Maewyn Succat, but he changed it to Patricius after becoming a priest.

12. There are no female leprechauns.

Vintage St. Patrick's Day postcard.
Turns out, leprechauns might have earned that pot o' gold.
Don The UpNorth Memories Guy, Flickr // CC BY-ND-NC 2.0

Don’t be fooled by any holiday decorations showing lady leprechauns. In traditional Irish folk tales, there are no female leprechauns, only nattily attired little guys who spend their days making and mending shoes (meaning they earned that gold they're always guarding).

13. St. Patrick's Day lingo makes sense.

Vintage
It basically means "Ireland forever."

You can't attend a St. Patrick’s Day event without hearing a cry of "Erin go Bragh." What's the phrase mean? It's a corruption of the Irish Éirinn go Brách, which means roughly "Ireland Forever."