St. Patrick’s Day is Thursday, but some Americans started celebrating two weeks ago. The city of Alexandria, Virginia, held its annual St. Patrick’s Day Parade on March 5. So did three cities in New Jersey. The holiday is a big deal in America and not only for the 33.1 million Americans who claim Irish ancestry. Many non-Irish Americans will join Irish friends in wearing green clothes on Thursday. Many will lift a mug of Guinness, the famous Irish beer. At a Washington, D.C., luncheon this week, President Barack Obama made a note of how big St. Patrick’s Day has become. “Now, it’s true that it’s not technically St. Patrick’s Day, but that's OK,” Obama said. “Most folks who celebrate it aren’t Irish either.” The holiday honors Saint Patrick, the patron saint of Ireland. Patrick lived in the 5th century. He was taken by pirates and kept as a slave in Ireland. After he escaped, he trained as a priest before returning to Ireland. “Patrick preached and converted all of Ireland for 40 years,” wrote Catholic Online.