Need an example of how holiday celebrations change over time? Look no further than March 17. It marks the anniversary of the death of Saint Patrick, the patron saint of Ireland, in 461 CE. St. Patrick’s Day, as it’s now called, began as a Catholic feast day in 1631 CE. It falls in the midst of the season of Lent. During Lent, many Catholics fast and spend time in quiet prayer. Some saw St. Patrick’s Day as a chance to let loose a little as spring approaches. Legend says that to keep people from partying too much during Lent, the Church installed the cross-like four-leaf clover as a symbol of the day. The symbol stuck. So did the parties. Today, the holiday is hugely popular in the US. Much of its religious tone has been downplayed. People dress in green to celebrate. Here are a few ways cities around the US will mark “St. Paddy’s” this year: New York City: Home of the oldest St. Patrick’s Day parade in the world, New York will again host the annual march, which takes more than 150,000 participants up Fifth Avenue and past St. Patrick’s Cathedral. Founded in 1762, the celebration of New York’s Irish heritage is expected to draw over 2 million spectators. Chicago: In perhaps the most iconic of all St. Patrick’s celebrations, Chicagoans will once again flock to the banks of the Chicago River, which will be dyed green. The chemical composition of the dye is a carefully-guarded secret, but officials have promised it’s eco-friendly. San Diego: The southern California city invites its community to the beach for the Oceanside Irish Festival. Highlights include the transformation of San Diego’s Gaslamp Quarter into an Irish village, complete with traditional foods, live Celtic music, and Irish games. Reflect: What are some reasons that holiday celebrations change over time? Gif of Happy St. Patrick’s Day from Giphy.