The history of junk food and fast food is wrapped up in the industrialization of America. Before the early 1800s, food was almost exclusively prepared in the home and made with minimally processed ingredients grown locally and harvested seasonally. That's not to say that people ate healthy and varied diets, but the very idea of junk food − highly processed, commercially manufactured snacks − didn't exist.
Andrew F. Smith, a food historian and author of "Fast Food and Junk Food: An Encyclopedia of What We Love to Eat", credits the industrialization of flour mills in the 1820s with the launch of the junk food era [source: Smith]. Innovations in milling technology and improvements in transportation brought inexpensive white flour to the masses. Even today, cheap white flour is the foundation of low-fiber, high-carbohydrate burger buns, cookies and snack cakes.
During the American Civil War (the 1860s), troops grew accustomed to eating from cans and jars of mass-produced rations. They came home craving the same convenience and familiar tastes. The rise of the industrial factory drew people away from farms and into the city. Food vendors parked their carts outside the factory gates, offering the first "fast foods" to hungry workers [source: Smith].
The first great American junk food was Cracker Jack, a salty-sweet blend of popcorn, molasses and peanuts introduced by brothers Frederick and Louis Rueckheim at the Chicago World's Fair in 1893 [source: Fernandez]. The recipe wasn't a novelty, but the Rueckheim brothers' true genius was marketing − a prize in every box! − and their trademark wax seal packaging. By 1916, Cracker Jack was the best-selling snack in the world [source: Smith].
The history of soft drinks goes all the way back to 17th-century Europe, where carbonated water was first mixed with lemon juice and honey for a bubbly sweet concoction [source: Korab]. In America, the first batches of Coca-Cola and Pepsi-Cola syrup were mixed at pharmacy counters in the 1880s and 1890s and sold as a refreshing, healthy elixir to aid digestion [sources: The Coca-Cola Company, Pepsi-Cola].
The emergence of fast food was fueled by the rise of automobile culture and the suburbanization of American cities in the 1950s [source: Smith]. Originally a convenient novelty, ordering a burger and fries at the "drive-thru" soon became an American institution.
The second half of the 20th century witnessed explosive growth in the variety, affordability and ubiquity of junk food and fast food. Innovations in manufacturing, packaging, transporting and marketing junk food − particularly to children − turned a rare treat into a steady diet for millions. And all the big companies employ an army of food scientists who know just how to get us coming back for more.