Realism and Naturalism emerged as influential literary movements in late 19th-century America. These styles aimed to depict life truthfully, focusing on ordinary people and everyday situations. They rejected romanticized ideals, instead emphasizing objectivity and social criticism. Key authors like Mark Twain and Stephen Crane pioneered these movements, exploring themes of determinism and social inequality. Their works reflected the rapid changes of post-Civil War America, addressing issues of industrialization, urbanization, and class struggle that continue to resonate today.