Today marks National Popcorn Day. Movie theaters across the country will be celebrating with special offers. AMC Theaters will be giving moviegoers unlimited refills on every size of popcorn all day today. Cinemark will discount medium and large popcorn by two dollars at their theaters. Dine-in theater chain Alamo Drafthouse will be giving out free bowls of popcorn with the purchase of a movie ticket and any food or beverage item. Americans consume around four-and-a-half-billion quarts of popcorn at movie theaters and other live venues each year, according to the National Association of Concessionaires.