In the past, Saint Patrick's Day was celebrated only as a religious holiday. It became a public holiday in 1903, by the Bank Holiday (Ireland) Act 1903, an Act of the United Kingdom Parliament introduced by the Irish MP James O'Mara. O'Mara later introduced the law which required that pubs be closed on 18 March, a provision which was repealed only in the 1970s. The first St. Patrick's Day parade held in the Irish Free State was held in Dublin in 1931 and was reviewed by the then Minister of Defence Desmond Fitzgerald. Although secular celebrations now exist, the holiday remains a religious observance in Ireland, for both the Church of Ireland and Roman Catholic Church.This is also the time of year Americans intersperse their conversations with quips about how Irish they are by using scientifically proven fractions and marital status. It's a custom about as old as the holiday itself, I'd wager.