The 1930s was a decade that began in depression after the Wall Street Crash of 1929, the largest stock market crash in American history. This decade was marked by the deepest and longest lasting economic downturn in the history of the Western industrialized world. The Great Depression had a traumatic effect worldwide and led to widespread unemployment and poverty, deeply affecting the soul and conscience of this nation. As people sought diversion from their troubles, the 1930s saw the marked growth of mass culture, including film, music and literature. Most popular culture centered on escapist themes and/or humor. This decade was dominated by the presidency of Franklin D. Roosevelt who put into place relief and reform measures that helped lessen the worst effects of the Great Depression. The 1930s also saw a proliferation of new technologies, especially in the fields of intercontinental aviation, radio, film (history.com). The economy would not fully recover until after 1939 when World War II helped to put American industry into high production mode.