Probably no decade saw as many changes in the Hollywood film industry and its product as the 1930s did. By 1939, popularly called "Hollywood's Greatest Year, " films like Gone With the Wind and The Wizard of Oz used both color and sound to spectacular effect, and remain American icons today. The "mature oligopoly" that was the studio system had not only weathered the Depression and become part of mainstream culture through the establishment and enforcement of the Production Code, it was a well-oiled, vertically integrated industrial powerhouse. The ten original essays in American Cinema of the 1930s focus on sixty diverse films of the decade, including Dracula, The Public Enemy, Trouble in Paradise, 42nd Street, King Kong, Imitation of Life, The Adventures of Robin Hood, Swing Time, Angels with Dirty Faces, Nothing Sacred, Jezebel, Mr. Smith Goes to Washington, and Stagecoach.