In many ways, fast food seems the perfect companion to Americans' "on the go" lifestyle. Prior to the rise of fast food in the 1920s, most Americans ate together at home most of the time. As the United States became more modernized and industrial, the pace of life sped up, helped in part by the growing use of automobiles. By the 1920s, more Americans were busier going from home to work and to all kinds of leisure activities than they ever were before. This made it harder to find time for home-cooked meals. The fast-food industry slowly emerged to take advantage of, and to promote, this trend.

Considered to be the first fast-food restaurant, White Castle has been cooking up its famous burgers and fries since 1921. Hulton/Archive by Getty Images. Reproduced by permission.

The first fast-food restaurant is generally considered to be White Castle, founded...