Uncle John knows pretty much everything—and if he doesn’t, he heads his massive research library, or puts one of his many associates on the case. So go ahead: In the comments below, ask Uncle John anything. (And if we answer your question sometime, we’ll send you a free book!) This week’s question comes from reader Kristen G., who asks…

How did popcorn come to be the quintessential movie snack?

Corn has long been an important crop to native peoples in the Western Hemisphere. Popcorn as we know it came via Central and South America by way of whalers. Historians think that New England whaling ships traveled to Chile and brought back different corn varieties, including the one whose kernels amusingly exploded when heated. By the middle of the 19^th century, popcorn was hugely popular as a snack at public entertainments across the U.S.—it was cheap, easy to prepare (just add heat), and fun to eat. Popcorn vendors were soon ubiquitous at circuses and fairs.

It wasn’t always a popular movie snack—like during the silent film era. Movie exhibitioners didn’t sell popcorn (or any snacks) for silent films, believing that the sound of people eating, slurping, and snacking—especially crunchy, noisy, popcorn—would be distracting and off-putting. When the “talkie” arrived, so, too did popcorn…but not from the theater itself. In the 1930s, street vendors paid to park their carts outside of a movie theater or in the lobby and sell their wares. Average cost: about five cents a bag.

Candy remained the most popular movie treat up until World War II, before popcorn took its place. The major reason: candy bar production in the U.S. went way down due to the war-caused shortage of labor and the war-caused rationing of sugar. Popcorn remained a cheaper and more viable offering. It was also remarkably profitable for the theaters, who by mid-century ran their own concession stands. A 100-pound bag of kernels might cost $10 in 1945…and make a few thousand bags.

Now, don’t ask us how they make that weird, butter-flavored stuff they put on the popcorn. Nobody knows what that stuff is.