Casseroles layered with corn tortillas go back to Mesoamerica, but the Fritos pie (or, if you wish, Frito pie) cannot, by definition, predate 1932. That is when Fritos were patented by Elmer Doolin, who got the recipe from a street-corner vendor and started selling them at his lunch counter in San Antonio. (Doolin subsequently invented Cheetos.) Long before Fritos, Mexicans had enjoyed eating fritos (small f), which simply means “little fried things,” but it was Doolin who figured out how to mass-produce the curly little corn chips, and it has been reported that it was his mother, Daisy Dean Doolin, who first put them into a baked casserole with chili and cheese.
Some thirty years later, at the Woolworth’s lunch counter in Santa Fe, cook Teresa Hernandez got the idea to create an individual Fritos pie by simply slicing off the top of a single-serving bag of chips and ladling in chili, then cheese, onions, lettuce, and tomato. She planted a plastic fork and, because Woolworth’s was right on the Plaza in the heart of town, her creation became a popular portable meal that visitors and locals could enjoy while on the stroll or sitting on a park bench.
Santa Fe’s Five and Dime serves its Fritos pie in the bag.
Like Fritos themselves, Fritos pie is no longer strictly regional, but it is especially popular across a wide swath of the Southwest from Arkansas through Texas and Oklahoma and into New Mexico. Variations encountered include Flagstaff pie in Amarillo and the Hot Springs spread, which also includes tamales.