St. Patrick’s Day is a tradition brought over by Irish-American immigrants in the 1700’s. A religious holiday in Ireland that stems back to the early 10th century, it is the observance of the Roman Catholic feast day in honor of St. Patrick. The holiday has changed over time to become a tradition of parades and festivities in honor of the Irish culture.

St. Patrick’s Day is celebrated on March 17, the date of St. Patrick’s death. Because St. Patrick is most prominently associated with bringing Christianity to Ireland, his legends are deeply embedded in Irish culture. Today, the holiday is widely observed as a celebration of Irish culture, much as it was when it began its spread through the U.S. in 1848.

When Irish immigrants began pouring into America in 1848 to avoid starvation due to the Great Potato Famine, they were despised. They were ridiculed for their celebration of their Irish heritage on March 17. Once they realized the power of their numbers to sway politics, they came together and their celebrations became a symbol of the strength of their heritage.

Many celebrate the Irish culture by enjoying Irish food and drink, such as corned beef and cabbage. Traditionally, those who don’t wear green on this holiday get pinched. There are many symbols associated with the holiday, including shamrocks, rainbows and pots of gold, and the American addition of the leprechaun. Leprechauns became associated with St. Patrick’s Day after Walt Disney released Darby O’Gill and the Little People, portraying a charming version of the Irish’s cantankerous little person.

Today, there are more than 100 parades across the U.S. to celebrate St. Patrick’s Day. The largest of these parades are held in New York City, Boston and Chicago also dyes the river green, which has been a tradition since 1962.