McDonald's first introduced the Big Mac at a restaurant in Pennsylvania in 1967.
The sandwich was created by Jim Delligatti, a McDonald's franchisee in the Pittsburgh area. He wanted a larger hamburger that would appeal to customers seeking a more substantial meal than the chain's standard offerings.
The Big Mac uses two beef patties, a three-part sesame-seed bun, lettuce, cheese, pickles, onions, and its distinctive sauce. It became one of McDonald's most important branded menu items and later spread throughout the United States.
Some references give 1968 because that was the year the Big Mac was introduced nationwide in the United States. The earlier Pennsylvania launch took place in 1967, which is the specific date asked here.