- In the 1940s, American artists distanced themselves from politically driven avant-garde styles and Marxism. Diego Rivera included communist imagery in his Rockefeller Center mural, causing controversy. - Surrealist artists like Andre Breton and Wolfgang Paalen experimented with automatism and techniques like frottage and fumage. Many European surrealist artists fled to the US to escape Nazi persecution. - Abstract expressionism emerged in the late 1940s in New York, exemplified by artists like Pollock, Rothko, Motherwell, and de Kooning. Pollock's drip paintings in the late 1940s were especially influential in establishing this new American style of abstract art.