America is getting green and giddy for its largest St. Patrick's Day parades

America's largest St. Patrick's Day parades are being held Saturday. While the St. Patrick's Day holiday is March 17, it's celebrated early when it lands on a Sunday. Enormous crowds are expected in Savannah, Georgia. A humble St. Patrick’s parade held in 1824 has grown to become the South's largest. In New York City, 2 million people regularly turn out for the main parade in Manhattan. In Chicago, plumbers will once again turn the Chicago River green. They use a powder that organizers say is not harmful to the environment.