Before products could be swiped across the UPC scanner to be checked out, cashiers had to manually enter in prices and store managers had no idea how much of the product was left in stock without taking inventory. Enter Drexel University graduate students Bernard Silver and Norman Joseph Woodland, who first began working on a self-checkout and inventory-control system in 1948, going through several variations that proved to be either too unweildy or too costly before accidentally hitting upon the right one.

On this day, June 26, in 1974, a supermarket cashier in Troy, Ohio slid a multipack of Wrigley’s chewing gum across a bar-code scanner, making it the first product to be checked out with a Universal Product Code.

Woodland should take most of the credit for developing the UPC code. He was thinking of applying Morse code to the products, but the dots were too hard to read unless placed exactly at the right angle. Idly drawing the dots and dashes in the sand while relaxing one day, he started elongating them with his fingers and suddenly realized that the resulting lines were much more visible and could be read from any angle.