The Big Mac was introduced in 1967 and became McDonald’s signature burger.
Jim Delligatti, a McDonald’s franchisee in the Pittsburgh area, created the sandwich after developing a larger burger for customers who wanted a more substantial meal. The Big Mac used two beef patties, a middle bun section, lettuce, cheese, pickles, onions, and the sauce associated with the sandwich.
It first appeared at selected McDonald’s restaurants in 1967 and was added to the national United States menu in 1968. Its three-part bun and memorable name gave the product a strong visual and verbal identity that supported McDonald’s branding.
The Big Mac’s introduction date is sometimes given as 1968 because that was its national rollout year. The more precise history distinguishes the 1967 regional introduction from the 1968 nationwide addition. Both dates are useful, but the question asks for the first introduction.