But while wind and water may leave millions of trick-or-treaters high and dry, Sandy won't likely affect Halloween sales—most people have already bought their holiday goods, the U.S. National Retail Federation's Kathy Grannis told Advertising Age.

Over the centuries, Halloween's already weathered a lot of changes, and we've summed them up here for you—along with the latest facts and figures for 2012: most popular costumes, record-breaking pumpkins, and more.

BEYOND HALLOWEEN 2012: HISTORY OF HALLOWEEN

Halloween's origins date back more than 2,000 years. On what we consider November 1, Europe's Celtic peoples celebrated their New Year's Day, called Samhain (SAH-win).

On Samhain eve—what we know as Halloween—spirits were thought to walk the Earth as they traveled to the afterlife. Fairies, demons, and other creatures were