When did using pepperoni as a pizza topping happen?

Pepperoni became a popular Pizza topping in the United States in the early to mid-20th century, particularly after World War II. While its origins can be traced back to Italian salami, it was American immigrants who adapted the recipe and made it a staple on pizzas. By the 1950s, pepperoni had solidified its status as the most popular pizza topping in the U.S.