Fast food as we know it today was really a product of the atomic age. McDonald's was the first to really brake out from the traditional mom and pop vibe which was a result of Ray Kroc and his success in franchising. By the time he took McDonald's public there was a string of copycats and America was hooked. Now if you consider the drive in to be fast food, they had already sprung up across the country but we're relatively independent and they did not have the same financial success of traditional fast food establishments of the 1950s and 1960s. If your interested I would highly recommend Lisa Napolis book on Ray Kroc and McDonald's.