On June 26, 1974, a checkout employee at a Marsh supermarket in Troy, Ohio became the first person to scan a grocery item—a pack of Wrigley’s Juicy Fruit chewing gum—using a Universal Product Code (UPC). Better known as a barcode, UPCs soon became ubiquitous, used everywhere from grocery and retail stores to hospitals and Mars rovers.

The innovation arose as a way to solve the manual, time-consuming processes that plagued grocery stores, but it transcended its original purpose, changing not only the way people shop but also how they share information.

Paul V. McEnroe, who led the team that created the barcode, expected the invention to take off but says he couldn’t have imagined its long-lasting impact. “We didn't have a real feel that it would be as big as it was for as long as it was,” he says.

While the UPC code launched in 1974, it was not the first attempt to create a system that could identify and classify products and get shoppers through checkout lines more efficiently. Back in 1949, Norman Joseph Woodland and Bernard Silver filed a patent application for a “classifying apparatus and method.” Known as the bull’s-eye code, their invention featured concentric circles.

One day, while running his fingers through sand at the beach, Woodland realized that lines of varying width could represent data in the same way that dashes and dots do from Morse code. While it was a great concept, it required a 500-watt light and a special tube to convert light into code.

“It’s an interesting example of a technology invented before its time,” says Jordan Frith, Pearce Professor of Professional Communication at Clemson University and author of Barcode. “The problem was it [needed two] things. It needed computers to be cheaper. But most importantly, there was no easy way to read it.”

Meanwhile, others tried to make similar systems work. For example, the KarTrak system launched in 1967 to help identify and track freight on trains. This system, Frith explains, featured colored barcodes that could be scanned to identify trains and their cargo as they were moving.

“They went by fixed-laser scanners. They would detect the cars in real time,” Frith says. KarTrak ultimately failed, however, due to a range of factors, including a lack of integration with computer systems, and the fact that snow or mud could obscure the code and lead to faulty readings.

Two years later, in 1969, IBM was looking to expand its business in new areas by buying startups. However, according to McEnroe, who was an IBM employee at the time, employees of these smaller companies would often quit because they didn’t want to work for a business that was so rigid, one where, as McEnroe says, “you have to wear a white shirt and blue suit every day,” So IBM decided to look within.

As McEnroe explains, a top IBM executive was looking for someone who could “do their thing without the oversight that would kill the project, without… having to make a certain profit the first year.” Fresh off getting a business degree at Stanford University and working out of Silicon Valley, McEnroe was eager to take on this vague initiative.

“I had the opportunity to go into any field I wanted, except [for] oil exploration…but anything related to computers,” says McEnroe, who authored his account in The Barcode: How a Team Created One of the World’s Most Ubiquitous Technologies.

McEnroe, who had spent nine years working in scanning, alongside marketing professional Sarkis Zartarian and engineer Mort Powell, developed a proposal for IBM to enter the point of sales industry. Once funding was secured, McEnroe assembled a team, known within the company as Consumer Transaction Systems. The team was made up of experienced engineers, most of whom had never worked with point-of-sale devices.

“That meant we had a slow start as these engineers taught themselves this new subject,” he writes. “But it also meant that they were not constrained by prior art—no one had told them what _couldn’_t be done.”

George Laurer was a key part of that and proved fundamental in the barcode’s invention. Laurer (who died in 2019) later wrote that there was an initial push to develop the bull’s-eye barcode, but he knew that wouldn’t work. “It was obvious to me that that approach would never satisfy all the requirements over the long run,” he wrote. Instead, he pushed for linear bars and an X on the scanning window. “With a simple ‘X,’ linear bars could be read no matter how they were oriented in the scan window,” he wrote.

In 1970, the National Association of Food Chains (NAFC) created a committee to determine if item identification was viable. The IBM team completed a version of their UPC code in 1971 and submitted their design when the committee asked for proposals in 1972.

There were seven finalists, including the code Woodland and Silver had devised on a beach decades prior. The Radio Corporation of America (RCA) owned the patent at that point and submitted a proposal using the bull’s-eye code. However, as the IBM team knew, it posed issues.

“Anytime you have a circle of lines as opposed to straight bars, the circles, by the fact that they have to go all the way around and you have so many of them, they take up more space. And it’s very hard to control from a printing point of view,” McEnroe says, explaining printers would often spit out the round codes smudged at the edges.

Woodland had even called McEnroe to let him know that he didn’t want the bull’s-eye code to win. At the time, Woodland was working for IBM in New York and offered to join the Consumer Transaction Systems team. “He came to Raleigh, and he greatly supported us in getting our code selected,” McEnroe says.

As the committee continued to deliberate, the IBM team continued to innovate on its design to make it more precise. McEnroe proposed that the committee use new modifications it had made and claim the code as its own. Eventually, that’s what the committee did, and the UPC code was ready to launch.

The IBM team created hardware and software that made the barcode possible. However, when it came to rolling out the technology, there were a few challenges. The IBM team had to hire a company to prove that the laser scanners wouldn’t harm people. Also, when McEnroe sent engineers to a store in Tysons Corner, Virginia to debut the technology, labor union picketers, who worried UPCs would lead to job losses, didn’t let them inside. There was also Carol Tucker-Foreman, executive director of the Consumer Federation of America, who wanted to preserve individual item pricing because she argued that it took away consumers’ ability to shop comparatively.

“Carol Tucker-Foreman almost immediately began a nationwide battle against barcode adoption,” Frith says. “There were senate hearings. She held town halls. She did debates.”

“Eighteen states, as I counted at the time, passed laws against using the scanner in the store without removing the prices,” McEnroe says. “In other words, they would let you use a scanner, but they would not let you remove the price from the item. And, of course, removing the price from the item was one of the big cost advantages that the supermarkets were using to pay for the equipment in the first place.”

Consumer backlash against the barcode eventually subsided and, by the early 1980s, more and more grocery stores began adopting the technology. By 1989, barcodes were used in more than half of all U.S. grocery sales.

While McEnroe calls the invention of the UPC code a team effort, he argues that if any one person deserved recognition, it was Laurer, who was inducted into the Engineering Innovation Hall of Fame for his invention. Meanwhile, the UPC Code went on to become used internationally and change the way people shop, and making it possible for superstores with countless products to exist.

While McEnroe and his team couldn’t have fathomed just how widespread the barcode would become, he thinks it’s a positive that no one became rich off of the barcode patent. To submit the code to the NAFC, every entity had to agree to forego ownership.

“The supermarket institute had the vision to say that it had to be in the public domain,” he says. “These were just really good, top-notch engineers that rolled up their sleeves, came to work every morning, and just tried to figure out how to make this thing work better and more effectively for everybody in the world.”