The story of the invention of Doritos is an interesting one. Back in 1955, just months after opening Disneyland, the founder of Frito-Lay, a man named Elmer Doolin, presented an idea to Walt Disney, suggesting that he allow Doolin to open Casa de Fritos, a Mexican restaurant, in Frontierland in a strip of restaurants called New Orleans Street.
Back in 1955, Mexican food was rather exotic to American tastes. The restaurant sat alongside Aunt Jemima's Pancake House (I remember their “Mickey Mouse pancakes”). Casa de Fritos served tamales, chili, Frito pie, enchiladas and something reportedly called the “Ta-Cup.”
As the story goes, a batch of discarded tortillas was saved from the trash and transformed into an off-menu item that became an instant hit. It was one of the route salesman who saw discarded tortillas and told the cook to make them into tortilla chips instead of just tossing them in the trash. You see, at that point, tortilla chips weren't part of the Frito family, so the restaurant had no use in offering them as other Mexican restaurants did. Casa de Fritos put them on the menu—without the knowledge of the Frito Co.
According to a book called “Taco USA” by Gustavo Arellano, the marketing vice president for Frito Lay, Arch West, passed by Casa de Fritos and noticed customers eating the chips. In 1966, the chips went national, called Doritos ("little golden things), and were an immediate hit.
And Doritos were born.
Source: OC Weekly