Popcorn was cultivated and cooked in North America since at least around 2000 BC. After North America was colonized, popcorn became a popular food from the 1890s, being one of the few successful confections during the great depression and becoming a movie theater staple in the late 1920s.

Source: https://www.popcorn.org/All-About-Popcorn/History-of-Popcorn