The availability of inexpensive loaves of bread and processed cheese was the catalyst for making the grilled cheese sandwich a staple of the common person’s diet in the 1920’s.
In its earliest form, a grilled cheese sandwich was prepared open faced with grated American cheese. Eventually, people began closing the sandwich with a second piece of bread – mainly to make the meal a more filling one. The grilled cheese sandwich was a mainstay during the American Great Depression of the 1930’s. Down on their luck citizens could usually afford an inexpensive grilled cheese and the meal provided sufficient nutrition to keep them going for a few hours more.
It’s also worth noting that the actual term “grilled cheese” doesn’t make an appearance in print until the 1960’s; it was all “toasted cheese” or “melted cheese” sandwiches before then. Which speaks to a larger point: how you actually cook this sandwich doesn’t really matter, and historically the methods have been all over the map. As early as 1902, a recipe for a “Melted Cheese,” designed to be cooked in a hot oven, appeared in Sarah Tyson Rorer’s Mrs. Rorer’s New Cook Book; a recipe published in 1929 in Florence A. Cowles’ Seven Hundred Sandwiches called to broil the ingredients to make “Toasted Cheese.” “Toasted Sandwich,” published in 1939 in The Boston Cooking School Cook Book, encouraged the ingredients to be broiled or even—gasp! —sautéed in a frying pan coated with butter. And in The Joy of Cooking (1953), Irma S. Rombauer wrote that bread and cheese should be heated in a commercial waffle iron—an easy meal for even “the maid less host” to prepare.