(Pressure is equal to average force / unit area)." Popcorn can be cooked with butter or oil.
At least six localities (all in the Midwestern United States) claim to be the "Popcorn Capital of the World;": Ridgway, Illinois; Valparaiso, Indiana; Van Buren, Indiana; Schaller, Iowa; Marion, Ohio; and North Loup, Nebraska.
According to the USDA, corn used for popcorn production is specifically planted for this purpose; most is grown in Nebraska and Indiana, with increasing area in Texas.
By the turn of the century, Cretors had created and deployed street carts equipped with steam powered popcorn makers.
During the Great Depression, popcorn was fairly inexpensive at 5–10 cents a bag and became popular.
The six major types of corn are dent corn, flint corn, pod corn, popcorn, flour corn, and sweet corn.
Popping of the kernels was achieved by hand on the stovetop through the 19th century.
Some strains of corn (taxonomized as Zea mays) are cultivated specifically as popping corns.
The Zea mays variety everta, a special kind of flint corn, is the most common of these.
The pressure continues building until it exceeds the hull's ability to contain it.
The kernel ruptures and forcefully expands, allowing the contents to expand, cool, and finally set in a popcorn puff 20 to 50 times the size of the original kernel.
Cretors successfully introduced his invention at the Columbian Exposition in 1893. Cretors's invention introduced the first patented steam-driven popcorn machine that popped corn in oil.