7 St. Patrick's Day, Traditions Explained. Everyone is Irish on St. Patrick's Day, but why are these traditions so significant?. 1. St. Patrick. Patrick was an Irish missionary who was kidnapped as a child and brought to Ireland. March 17 is believed to be the day of his death. 2. The Green River in Chicago. The Chicago River has been traditionally dyed green for over 50 years. The color green is derived from the green strip in the Irish flag. 3. Parades. The first St. Patrick’s Day parade in the U.S. was in 1762. They allow people to proudly celebrate their Irish-American identity. 4. Shamrocks. Shamrocks used to be worn by the Irish in defiance of the ruling British class and to represent kinship among the native people. 5. Drinking Guinness. This Irish stout is the drink of choice on St. Patrick's Day, with about 13 million pints consumed on the holiday. 6. Leprechauns. These little green men come from 8th century Irish folklore. They were said to make shoes and wreck havoc on unsuspecting humans. 7. Corned Beef and Cabbage. This tradition was begun by poor Irish-Americans of the 19th century. Corned beef and cabbage were the affordable option