The Big Mac, created by franchisee Jim Delligatti, debuted nationally at McDonald's in 1968.
Delligatti operated McDonald's restaurants in the Pittsburgh area and developed the sandwich after experimenting with a larger, two-patty format. The final version used two beef patties, a middle bun section, lettuce, cheese, pickles, onions, and the sauce later strongly associated with the product.
The sandwich had appeared in selected locations before its nationwide rollout. Its name and distinctive three-part bun gave McDonald's a flagship product that was easy to recognize in advertising and restaurant menus around the world.
The Big Mac is sometimes confused with the Quarter Pounder because both became signature McDonald's menu items. The Quarter Pounder is defined by its quarter-pound pre-cooked beef patty, while the Big Mac is defined by its two-patty layered construction.