Some famous 20th century American artists are Georgia O'Keeffe, Jackson Pollock and Andy Warhol. They lived from 1887-1986, 1912-1956 and 1928-1987, respectively.
Georgia O'Keeffe is often considered one of the most influential artists of the 20th century. Her work is characterized by abstract depictions of natural forms, as well as man-made cityscapes.
Jackson Pollock was also interested in abstractions and was one of the leading proponents of abstract expressionism. He is best remembered for his "splatter and action" work, for which he poured paint onto canvases.
Andy Warhol used a variety of media during his career. Interested in fame and mass-production, perhaps his best known paintings are of Campbell's soup cans and Marilyn Monroe.