<P> One of the most vocal critics of abstract expressionism at the time was New York Times art critic John Canaday . Meyer Schapiro and Leo Steinberg along with Clement Greenberg and Harold Rosenberg were important art historians of the post-war era who voiced support for abstract expressionism . During the early - to - mid-sixties younger art critics Michael Fried, Rosalind Krauss, and Robert Hughes added considerable insights into the critical dialectic that continues to grow around abstract expressionism . </P> <P> During the period leading up to and during World War II, modernist artists, writers, and poets, as well as important collectors and dealers, fled Europe and the onslaught of the Nazis for safe haven in the United States . Many of those who didn't flee perished . Among the artists and collectors who arrived in New York during the war (some with help from Varian Fry) were Hans Namuth, Yves Tanguy, Kay Sage, Max Ernst, Jimmy Ernst, Peggy Guggenheim, Leo Castelli, Marcel Duchamp, André Masson, Roberto Matta, André Breton, Marc Chagall, Jacques Lipchitz, Fernand Léger, and Piet Mondrian . A few artists, notably Pablo Picasso, Henri Matisse, and Pierre Bonnard remained in France and survived . </P> <P> The post-war period left the capitals of Europe in upheaval, with an urgency to economically and physically rebuild and to politically regroup . In Paris, formerly the center of European culture and capital of the art world, the climate for art was a disaster, and New York replaced Paris as the new center of the art world . In Europe after the war there was the continuation of Surrealism, Cubism, Dada, and the works of Matisse . Also in Europe, Art brut, and Lyrical Abstraction or Tachisme (the European equivalent to Abstract expressionism) took hold of the newest generation . Serge Poliakoff, Nicolas de Staël, Georges Mathieu, Vieira da Silva, Jean Dubuffet, Yves Klein, Pierre Soulages and Jean Messagier, among others are considered important figures in post-war European painting . In the United States, a new generation of American artists began to emerge and to dominate the world stage, and they were called Abstract Expressionists . </P> <P> The 1940s in New York City heralded the triumph of American Abstract expressionism, a modernist movement that combined lessons learned from Henri Matisse, Pablo Picasso, Surrealism, Joan Miró, Cubism, Fauvism, and early Modernism via great teachers in America such as Hans Hofmann from Germany and John D. Graham from Ukraine . Graham's influence on American art during the early 1940s was particularly visible in the work of Arshile Gorky, Willem de Kooning, Jackson Pollock, and Richard Pousette - Dart among others . Gorky's contributions to American and world art are difficult to overestimate . His work as lyrical abstraction was a "new language . He "lit the way for two generations of American artists". The painterly spontaneity of mature works such as "The Liver is the Cock's Comb", "The Betrothal II", and "One Year the Milkweed" immediately prefigured Abstract expressionism, and leaders in the New York School have acknowledged Gorky's considerable influence . The early work of Hyman Bloom was also influential . American artists also benefited from the presence of Piet Mondrian, Fernand Léger, Max Ernst, and the André Breton group, Pierre Matisse's gallery, and Peggy Guggenheim's gallery The Art of This Century, as well as other factors . Hans Hofmann in particular as teacher, mentor, and artist was both important and influential to the development and success of abstract expressionism in the United States . Among Hofmann's protégés was Clement Greenberg, who became an enormously influential voice for American painting, and among his students was Lee Krasner, who introduced her teacher, Hofmann, to her husband, Jackson Pollock . </P>

When did the center of the western art world shift from europe to the united states