By the 1970s, McDonald's had grown into an increasingly popular fast-food establishment.
The Quarter Pounder, Quarter Pounder with cheese, and Egg McMuffin were also added to the menu.
National Burger Day is May 28, and no fast-food chain knows burgers quite like McDonald's.
In the 1970s, less than a decade into its operation under businessman Ray Kroc, McDonald's was already a thriving company that had served millions of customers.
Richard and Maurice "Mac" McDonald opened the first McDonald's in 1940 as a barbecue restaurant, and Kroc opened its first franchise location in Des Plaines, Illinois, on April 15, 1955. That year, he also founded McDonald's System, Inc., which would become the McDonald's Corporation we know today.
By 1958, McDonald's had sold 100 million burgers, and the restaurants had adopted a signature design style prominently featuring the chain's iconic "golden arches." In 1961, Kroc bought the McDonald brothers out, and by the 1970s, the company was going from strength to strength.
Today, there are around 34,000 McDonald's locations around the world, but there are also new challenges. Consumers are being more cautious about their spending, so the brand's focus this year is on offering affordable meal options amid surging global food prices, its execs said in May.
Here's what it was like to eat at McDonald's in the 1970s.
Before the introduction of high-tech cash registers, McDonald's employees would take down orders by hand to give to the kitchen.
Workers at a McDonald's take orders from customers in 1973.
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By the 1970s, the company was well-established and beginning its global expansion. In 1967, the first McDonald's restaurant outside the US opened in Richmond, British Columbia, according to McDonald's website. By 1970, the chain had sold over 6 billion burgers.
The self-service concept allowed customers to order at the counter and watch as their meal was being prepared by employees through a large window into the kitchen.
View along the counter of a McDonald's as employees serve a line of customers in 1979.
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McDonald's meals were served on plastic trays, which customers could then bring over to a dining-room table to enjoy.
McDonald's got its first drive-thru in 1975.
An employee makes burgers at a McDonald's restaurant in 1979.
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While chains like In-N-Out Burger already had drive-thru windows, McDonald's didn't have one until 1975, when a franchisee in Sierra Vista, Arizona, skirted around an Army regulation that prevented military members from entering local businesses in fatigues.
According to Fast Company, he got around the regulation by knocking down a wall in his restaurant's kitchen and installing a drive-thru window in order to serve them.
The menu at McDonald's in the 1970s already had a few familiar options.
An employee makes notes at the counter in McDonald's in Southfield, Michigan, in 1978.
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Before the 1960s, the McDonald's menu was simple. It included burgers, cheeseburgers, fries, milkshakes, and other fast-food classics. The first new item to be added to the national menu was the Filet-O-Fish sandwich in 1965, followed by the iconic Big Mac in 1968.
After the release of the Big Mac in 1968, the burger rose in popularity throughout the 1970s to become the chain's signature menu item.
A photo of a McDonald's Big Mac and fries from 1979.
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In 1973, the chain added two more signature burgers to its menu: the Quarter Pounder and Quarter Pounder with cheese.
In 1979, Happy Meals were introduced to attract parents who wanted to feed all family members at a great price.
In 1972, McDonald's began offering breakfast for the first time.
Workers at a McDonald's bag hamburgers in 1973.
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The introduction of the Egg McMuffin marked a turning point for the brand, attracting a wide customer base at a new time of day.
Dining in at McDonald's was popular among families, who could sit, grab a cheap bite, and even play cards.
A family plays cards and eats at McDonald's.
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In this photo, a family plays cards at a McDonald's in Mill Valley, California, in 1973.
This is what Ronald McDonald looked like in 1974.
Ronald McDonald meeting children from the Far West Home at Taronga Zoo in 1974.
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Ronald McDonald was introduced in 1963 during a Washington, DC-marketed advertisement for the restaurant. In the ad, Ronald McDonald pulled hamburgers out of his belt and had a McDonald's cup for a nose. His hat was a tray with a Styrofoam hamburger, fries, and a milkshake on top of it.
McDonald's considered changing Ronald McDonald's character to a cowboy or spaceman, but those ideas were quickly discarded.
For kids who grew up in the 1970s, there was no better place to celebrate a birthday than McDonald's.
A child named Vincent celebrates his 11th birthday at McDonald's in 1973.
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Fast Company reported that the first McDonald's PlayPlace was introduced in 1971, forever changing the McDonald's dining experience for families and children. While parents relaxed and ate their meals, kids could play in colorful climbing structures, jungle gyms, and slides.
The introduction of the PlayPlace solidified McDonald's reputation as a destination for families on a budget, as many were during the 1970s amid a time of financial insecurity, high inflation, and the Vietnam War.
You could even get married at McDonald's.
Annette Scaramozza and Anthony Francis at their wedding ceremony.
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Annette Scaramozza and Anthony Francis are pictured at their wedding ceremony in a McDonald's in 1975.
