St. Patrick’s Day is the feast day of St. Patrick, a patron saint of Ireland. Originally celebrated with religious feasts and services, St. Patrick’s Day became a secular celebration of Irish culture when it reached the United States alongside Irish immigrants.St. Patrick’s Day is celebrated annually on March 17, the anniversary of St. Patrick’s death in 461.St. Patrick’s Day was originally celebrated in Ireland with religious services and feasts in honor of St. Patrick, one of Ireland’s patron saints. When Irish immigrants brought St. Patrick’s Day traditions to the United States, the day evolved into a secular celebration of Irish culture. St. Patrick was a 5th-century missionary to Ireland who is credited with bringing Christianity to Ireland. He became a legendary figure by the end of the 7th century and is considered a patron saint of Ireland.