Final answer:
Ezra Pound is credited with introducing the Modernist Movement to the United States, emphasizing the need to 'Make It New!' in literature and the arts during the 20th century.
Step-by-step explanation:
The author often credited with bringing the Modernist Movement to the United States is Ezra Pound, whose credo "Make It New!" encapsulated the essence of modernism's drive to reinvent art, literature, and cultural ideals. American modernism is characterized by progressive transformations and an optimism towards the future, often driven by the challenging social, political, and cultural conditions, including the impact of World War I. Modernism in literature captured new forms of expression, innovation in narrative style and prose, and a desire to break with the past.