We found our answer in Ideas that Changed the World by Julie Ferris et al. and World of Invention, edited by Kimberly A. McGrath. Joseph Woodland and Bernard Silver patented the bar code in 1949. They had been looking for something that would be able to quickly and easily identify products at the supermarket, considering Morse code, when Woodland was inspired by going to the beach and drawing lines in the sand.
There weren’t yet any lasers or computers that could properly read the codes, and, unfortunately, Silver died in 1963 before his and Woodland’s idea could come to full fruition. Woodland kept at it and finished developing the UPC (which stands for Universal Product Code) by the early 1970s.
In either 1973 (according to World of Invention) or 1974 (according to Ideas that Changed the World), the first item – a pack of gum – was rung up at the supermarket using its new UPC code. Bar codes aren’t only used in supermarkets, though. They were used early on to identify railroad cars and, of course, you can find them on our library books!