Popcorn really took off in North America in the mid-1880s, but it would take 50 years for it to become a favorite food at movie theaters. According to Andrew Smith, author of Popped Culture: A Social History of Popcorn, "movie theaters wanted nothing to do with popcorn because they were trying to duplicate what was done in real theaters. They had beautiful carpets and rugs and didn’t want popcorn being ground into it.” Then the Great Depression happened and movies took off as popular cheap entertainment. Popcorn vendors set up outside to provide an equally cheap snack. By the early 1930s, a Kansas City entrepreneur named Julia Braden convinced theaters to allow her to bring her popcorn kiosk into the theater. Of course, eventually the theaters established their own concession stands. This week, both Smithsonian and the New York Times looked at the history of movie popcorn.
"Why Do We Eat Popcorn at the Movies?" (Smithsonian)
Who Made Movie Popcorn? (NYT)