In the first part of the 20th century, the American novel became the popularly preferred literary genre. At the same time, it diversified to keep pace with an increasingly rapid process of cultural and economic change. The modern novel was called upon to give voice to issues of nationalism, expatriation, and immigration; the rise of science and technology; the decline of religion and increasing influence of psychology and psychoanalysis; the emphatic shift to urban lifestyles; racial and class conflict; polarized political views of the Left and Right; increasingly acute perceptions of social violence; women's issues; the foregrounding of commercial and business interests in everyday life; such literary movements as modernism and naturalism; literary renaissances in Harlem and in the South; socialism and communism; the increasing popularity of formula fictions like the romance, the crime novel, and the Western; and events like World War I, Prohibition, the Jazz Age, the Great Depression, the New Deal, and World War II.