There are over 36.5 million U.S. residents who claim Irish ancestry. To put that in perspective, it's almost nine times the population of Ireland itself, which is over four million people. It's no wonder that St. Patrick's Day creates such a buzz all the way here in America!
Contrary to what you may think, St. Patrick's Day began as a very traditional religious time of year, until March 17th, 1962, when the first St. Patrick's Day Parade was conducted by Irish members of the English military through New York City. This prompted the creation of many "Irish-Aid" societies, who began to host their own parades with bagpipes and drums. In 1848, several societies all combined their parades to form one large New York City Parade, which has become the world's oldest civilian parade and the largest in the United States, with over 150,000 participants (or 300,000 legs, for you riddle solvers).
Currently, more than 100 parades are held all across the U.S., and St. Patrick's Day has even been celebrated in places like Singapore and Japan! In Ireland itself, laws mandating that pubs be closed on March 17th lasted until the 1970's. Beginning in 1995, the Irish government has begun using St. Patrick's Day as a means to showcase itself to the world, hosting a huge multi-day festival, in which close to a million people participated in last year.