Ad for Diet-Rite Cola – May 28, 1964. Marketed as “America’s Most Modern Cola”, it promised full cola flavor with absolutely no sugar and not even one calorie per bottle. At the time, Diet-Rite was the first nationally distributed diet soft drink in the U.S.

So in 1963 Pepsi released Patio Cola, a 1 calorie drink. Later expanded to offer orange, grape and root beer flavors, which didn’t last long. The next year, they dropped Patio in favor of the name Diet Pepsi.

Coca-Cola retaliated by releasing Tab in 1963 as well, and also later experimented with other flavors. Even after Diet Coke was released in 1980, Tab found a cult following and continued to be produced until 2020.