Jim Delligatti was frustrated. It was 1967, and Delligatti had been running a McDonald’s franchise for eight years. His market was Pittsburgh, and his bread-and-butter customers—men trudging to and from the steel mills—brought huge appetites in the door. But all Delligatti had for them was a regular cheeseburger. That’s when he decided to experiment a little. He put two beef patties into a new burger, adding lettuce, pickles and onions, plus a center bun to stabilize the thing. Finally, he added a “special sauce”—Thousand Island dressing, some have chided, though the recipe remains a secret. Delligatti was going to call his creation the “Big Mc,” but that didn’t sound right, so he opted for “Big Mac” instead. It may sound hyperbolic to say that Delligatti made history that day—except that he did. After Ray Kroc gave his blessing from headquarters, the Big Mac rolled out systemwide in 1968, introduced as “a meal disguised as a sandwich.” By 1969, the burger was generating 19 percent of McDonald’s revenue. Today, Americans consume 550 million Big Macs annually—a little more than one every second.Despite his mania for following the rule book, McDonald’s boss Ray Kroc (left) gave his blessing to the Big Mac, shown above in the hands of its inventor Jim Delligatti. The franchisee received no bonus or royalities from the sandwich, though he did turn one of his restaurants into the Big Mac Museum, whose treasures include a special-sauce injecting gun and a 14-foot-tall Big Mac. Big Mac: Larry “Bubba” Harmon; Kroc: The LIFE Images Collection/Getty Images It’s hard to think of any other single menu item that’s so utterly changed the restaurant business, even as it simultaneously became an icon of American culture. The Big Mac, says Charlie Hopper, principal with ad and marketing agency Young & Laramore, embodied McDonald’s core tenets of standardization—quick service, low prices and tasty (if not quite healthy) food that was consistent at all locations. By these means, the Big Mac “is like a metaphor for America,” Hopper said. “It lacks sophistication and is not particularly adventurous. It’s [just] a well-meaning, beefy thing.” The seeds: They might not add much in the way of flavor, but the sesame seeds (there are 400 of them on average) give the Big Mac its instantly recognizable look. The club bun: A true first was this center “club” bun, which kept the beef patties from slipping off each other and allowed the burger to achieve its signature height. The sauce: McDonald’s has never revealed exactly what’s in its fabled “special sauce,” but it did give away 10,000 bottles of the stuff in a limited-time promotion in January.Seeds: iStock; Big Mac: Todd Huffman McDonald’s debuts the Big Mac systemwide. Advertising Archive/Courtesy Everett Collection Improbably, it’s also continued to dominate the menu board for five decades mostly unchanged, even as consumer tastes have changed dramatically around it. As veteran restaurant consultant Aaron Allen points out, even the handful of products that have achieved that status take second place to the Big Mac. “Think about Barbie and how many times she’s had to be reinvented,” he said. “But this product remains relevant.” The key question for McDonald’s, Allen says, is how long the Big Mac can hold on to that relevance. Only one in five millennials has reportedly tasted a Big Mac, and McDonald’s menu tweaks have extended to its signature sandwich. Last summer, it nixed the high-fructose corn syrup in the buns, then introduced a scaled-down version (the Mac Jr), a response to “customers who told us they wanted different ways to enjoy” the item, corporate chef Mike Haracz said. Yet even the junior packs 27 grams of fat. A footnote for critics of the 540-calorie Big Mac: Delligatti continued to eat one each day until his death last year. He was 98.   Thanks Adweek