Karen Mansfield BURGER BIRTHPLACE — Cars line up in the drive-through of the Morgantown Street McDonald’s in Uniontown, Pa., home of the Big Mac. Every day, “the store’s very busy,” said manager Lindsay Brown, adding occasionally guests will pose with the sign outside or ask about the iconic burger.

UNIONTOWN, Pa. — I opened the box and there it was: Two all-beef patties, special sauce, lettuce, cheese, pickles and onions between a fluffy sesame seed bun.

At 30-something, I’d never had a Big Mac and figured the best place to try McDonald’s iconic sandwich the week of International Big Mac Day, celebrated annually Aug. 2, was in the place it all began: The McDonald’s along Morgantown Street in Uniontown.

“The first place to sell was Uniontown,” said Michael Delligatti, whose father, Michael James “Jim” Delligatti, debuted the Big Mac at the Uniontown Shopping Center Mickey D’s in 1967. “He actually was asking the corporation if he could do a bigger sandwich. Really all they had at that point was hamburgers, cheeseburgers. They kept saying no. While they were saying no, he kept fiddling around with some things.”

Jim Delligatti’s persistence prevailed, and the corporation agreed to let him experiment, so long as he used ingredients already found in McDonald’s restaurants. Delligatti mixed up a new kind of burger sauce and tried stacking two beef patties onto one sandwich.

“It was really messy on a regular hamburger bun,” Delligatti said. “He went to a bakery and said, ‘Can you make me a double cut bun?’ They said, yes.”

Jim Delligatti, who died in 2016 at the age of 98, ran ads for his new sandwich in the Herald-Standard, ads that included a coupon for 29-cent Big Macs. That was a steal, considering the original burger cost a whopping 45 cents.

Quickly sales soared to double-stacked burger heights, and Jim Delligatti introduced the Big Mac at his other Pittsburgh-area franchises – he was one of the first businessmen to franchise McDonald’s, and at one time owned 48 restaurants throughout Western Pennsylvania.

“They tried it (the Big Mac) locally here in Pittsburgh and it went so well, it was 10 percent or 12 percent of sales that year,” Delligatti, a McDonald’s franchise owner himself, said. “They launched it nationally. Now, they sell a few billion a year.”

By 1968, a year after its debut, the Big Mac was on the menu in every McDonald’s nationwide.

“I’ve been eating them since I was a kid,” said Dave Basinger of Connellsville when he placed an order for a Big Mac meal at the Morgantown Street location. “I like the sauce, the secret sauce.”

It’s no secret the Big Mac’s biggest draw is that sauce, a sweet and tangy dressing that starts tastebuds dancing.

“It’s my favorite sandwich. I want the extra sauce. I don’t care if it’s sloppy,” said James Spiker, who works maintenance at the Morgantown Street McDonald’s.

Dawn Mause of Smithfield, Pa., enjoys the versatility of Big Mac sauce.

“The sauce, I’ll get it on the side to dip chicken nuggets in,” Maust said, adding the Big Mac is a perfect blend of ingredients. “The cheese, when it’s all nice and melted together with the lettuce …”

Millions agree. McDonald’s sells about 550 million Big Macs a year, according to the corporation, more than any of its other burgers. And in Uniontown, Dan Masi, a grill cook, fires up dozens and dozens of Big Macs each shift.

“Definitely a couple hundred,” he said, smiling. “There’s more to making a Big Mac. There’s three stages: Preparing, make sure sauce is on there and pickles, you gotta have pickles, serving.”

Jennifer Kaiser, assistant manager, said today people will order a Big Mac but substitute chicken in place of the seasoned burger patties. For many, though, it’s the original Big Mac that’s equal parts delicious and nostalgic that keeps them ordering the big little sandwich from Uniontown.

Recently June Rygelski, shift manager, served an older couple two Big Macs, one for each of them.

“They said they have not been to McDonald’s in 10 years. They wanted to just come in and try the Big Mac again – does it still taste the same from that many years ago?” Rygelski said. “They said everything was perfect, the fries, the Big Mac.”

“I think the fact that even after all this time, all the changes McDonald’s makes, that’s the one constant,” added Kaiser.

In my tasting notes — yes, my first Big Mac was a delightfully indulgent work assignment — I noted the blend of melty cheese, sauce and crisp lettuce that Maust mentioned, and wrote the sandwich was a sweet and tangy treat I couldn’t quite put into words.

“It’s not your average sandwich,” said Amy Chapman, Uniontown McDonald’s supervisor, noting her son recently tried his first Big Mac. “He liked it. I was like, well, what do you like about it? He said, ‘It’s just different.'”

Delligatti’s father never received royalties for the globally revered double-patty burger he invented, but he was presented a plaque for the achievement. Since April 1967, when the Big Mac debuted in Uniontown, the sandwich has amassed quite the following: There’s International Big Mac Day, the late Jim’s birthday, and the heavily trafficked Big Mac Museum in North Huntingdon, Pa.

“It’s hard to believe it just keeps going,” Delligatti said. “We get greater and greater numbers of people (enjoying Big Macs). Younger folks are just starting to, like you having your first Big Mac.”

Like so many before me, my first Big Mac certainly won’t be my last. I and others are grateful to Mr. Delligatti for pressing on, for mixing up that secret sauce and testing out his wild dream of a burger in Uniontown, all those years ago.