It’s 51 years old

In August 1968, a new super-burger called the McDonald’s Big Mac became available to customers across America. It had debuted the year before in a Uniontown, Pennsylvania, McDonald’s location, and the franchise founder, Ray Kroc, was a fan. With his approval, the Big Mac went nationwide, and the rest is history.
It was created for steelworkers

The mastermind behind the Big Mac was Jim Delligatti, the owner of the Uniontown restaurant that debuted it. In the 1960s, many of his regular customers were workers returning from a long day at the steel mills. They would arrive at McDonald’s ravenously hungry, and Delligatti quickly realized that the simple single-patty cheeseburger wasn’t filling them up. So he started experimenting, putting two patties on one burger and adding pickles and onions as well.
“Special Sauce” didn’t get that nickname until 1974

In original Big Mac ads that launched across America in 1968, the flavourful concoction was advertised as a “secret sauce.” It wouldn’t be called by the alliterative name we know today until 1974, when the historically catchy “Two all-beef patties, special sauce…” jingle debuted. Despite the name change, and the ingredients remaining classified for years.