McDonald's introduced the Big Mac nationwide in 1968 after franchisee Jim Delligatti created it.
Delligatti operated several McDonald's restaurants in the Pittsburgh area and wanted a larger sandwich for customers seeking a more substantial meal. His creation used two beef patties, a middle slice of bread, lettuce, cheese, pickles, onions, and the chain's special sauce. The extra middle bun became one of its defining features.
The sandwich was first tested regionally before McDonald's placed it on menus across the United States. Its name was selected from proposed alternatives and quickly became one of the most recognizable product names in fast food. The Big Mac also helped establish the idea of a signature sandwich as a major part of a franchise menu.
The Big Mac is often confused with the Quarter Pounder because both are flagship McDonald's burgers. The Quarter Pounder is defined by a larger single beef patty, while the Big Mac is defined by its two patties and three-part bun.