每年的3月17日，圣帕特里克节（St Patrick's Day），是纪念爱尔兰的主保圣人St Patrick主教（约385–461年）的节日。
公元432年，St Patrick受教皇派遣前往爱尔兰劝说爱尔兰人皈依基督教。圣帕特里克临危不惧，当即摘下一棵三叶苜蓿，形象地阐明了圣父、圣子、圣灵三位一体的教义。他雄辩的演说使爱尔兰人深受感动，接受了洗礼。461年3月17日，Saint Patrick逝世，爱尔兰人为了纪念他，将这一天定为St Patrick's Day，后来成为爱尔兰人的国庆节，同时也是北爱尔兰的银行休假日与爱尔兰共和国、蒙特塞拉特和加拿大纽芬兰与拉布拉多省的法定节假日。在加拿大其他地区、英国、澳大利亚、美国和新西兰，圣帕特里克节虽然广为庆祝，但不是法定节假日。
美国从1737年3月17日开始庆祝，一些爱尔兰绅士和商人们在美国马萨诸塞州波士顿聚会纪念St Patrick，并成立了爱尔兰慈善社团。1780年和1784年，费城和纽约先后成立了圣帕特里克友谊之子等团体，从此美国人无论是不是爱尔兰后裔，每年都数百万人上街庆祝这个全国性的节日。
美国是爱尔兰人移民最多的国家之一，据美国人口普查局的统计，截至2008年，自称具有爱尔兰血统的美国人约有3628万，占美国人口总数11.9%，爱尔兰裔美国人是仅次于德国裔美国人的第二大族群。爱尔兰裔美国人移民美国历史长久，人数众多，对美国社会的发展贡献良多，政治影响力十分可观。现代美国历史上的历任总统，大多具有爱尔兰血统，包括奥巴马、布什父子、克林顿、里根、卡特、尼克松、肯尼迪、杜鲁门等。
美国的St Patrick's Day这一天，人们通常要举行游行、教堂礼拜和聚餐等活动。美国的爱尔兰人喜欢佩带三叶苜蓿，用爱尔兰的国旗颜色——绿黄两色装饰房间，身穿绿色衣服，并向宾客赠送三叶苜蓿饰物等。
除了服装外，食品、玩具等在节日期间都会带上绿色。圣帕特里克节前后，爱尔兰酒吧总是挤满顾客，其他各种酒吧也比平时多了不少人，酒吧在节日期间还会出售特制的啤酒，颜色是绿色的，这种绿色啤酒很受欢迎，口味也很独特，销量很好。
(Wikipedia)
On March 17, many Americans — including non-Irish people — celebrate St. Patrick’s Day.
In the fifth century, Patrick was a bishop of the Catholic Church. He brought Christianity to Ireland through his teaching.
Why do Americans celebrate an Irish saint? Probably because of the large immigration from Ireland to the US. Some say that on St.Patrick’s Day, “Everybody is a little bit Irish.” In fact, today, almost 37 million Americans claim some Irish ancestry (see the chart below). This is a lot bigger than the current population of Ireland! While Irish-Americans can be either Catholic or Protestant, celebration of St. Patrick’s Day is usually seen as an act of connection to the (mostly Catholic) Irish Republic.
In the US, St. Patrick’s Day is a non-religious celebration of Irish culture. The spirit is one of fun and friendliness. You do not have to be Irish to join in. Your children may tell you that they are supposed to wear something green that day. It’s not a real school rule, but wearing green is a way of showing appreciation of Irish culture — its spirit, its music, its writing. But you will not offend anyone if you do nothing.
On St. Patrick’s Day, you’ll see parades, especially in cities with a large Irish-American population.
Many bars, especially Irish-style pubs, have special celebrations. If you are offered a green beer, don’t panic — it’s just green food coloring.
Gifts and cards are not part of the tradition of this day (although you will find plenty of green items to buy if you want to). St. Patrick’s Day is not a legal or business holiday.
