Fun Facts To Celebrate Grilled Cheese Day Each year, National Grilled Cheese Sandwich Day on April 12th recognizes one of the top comfort foods in the United States. Why wouldn’t it be when we’re talking about bread grilled to perfection, and warm, gooey, melted cheese. The United States modern version of the grilled cheese sandwich originated in the 1920s. As sliced bread and American cheese became easily available, Americans began making open-faced grilled cheese sandwiches. During the industrial revolution, Otto Frederick Rohwedder invented the bread slicer that made distributing slice bread more accessible and more affordable. Shortly before this invention, however, James L. Kraft created processed cheese. His process ensured that this cheese won’t spoil even when transported long distances. United States government cookbooks describe Navy cooks broiling “American cheese filling sandwiches” during World War II. Recipes for grilled cheeses have been mentioned in Ancient Roman texts, so the idea of grilled cheese goes back a long way. It is said that grilled cheese was first served as an open-face sandwich. Sliced cheese wasn’t introduced until the late 1940s when Kraft Foods introduced Kraft singles, and then years later supermarkets stocked them in the 1960s. The actual term “grilled cheese” doesn’t make an appearance in print until the 1960’s. Before then it was all “melted cheese” or “toasted cheese” sandwiches. Between the 1920s and the 1970s, the sandwich was called a “Cheese Dream“ In 2009, Los Angeles hosted the world’s first grilled cheese cooking competition: thousands and thousands of people competed at and attended the National Grilled Cheese Invitational, which has turned into a much-anticipated annual food festival. The most “grilled cheese loving” cities are Baltimore, San Diego and Cincinnati, according to UberEATS. UberEATS has also found that the most popular day of the week to order a grilled cheese is Saturday. The least popular day is Tuesday. 3/4 of people who buy sliced cheese make at least one grilled cheese per month. Sources: National Day Calendar Days of the Year Foodimentary Mobile-Cuisine Entrepreneur .