Fast food originated in the United States in the early 20th century as urban development increased and people's work and lifestyles became busier. Some early fast food restaurants and concepts included the Automat restaurant in 1912 which offered prepared foods behind small windows, White Castle hamburgers in 1921 which emphasized cleanliness, and Kentucky Fried Chicken starting in 1930 which sold fried chicken in front of a gas station. McDonald's, founded in 1948, was one of the first restaurants to use assembly-line production and helped popularize the fast food industry globally. Drive-through services became common in the 1950s, allowing customers to order and pick up food without leaving their cars.