1) depression lingered longer in Europe than in U.S.
2) repressive political regimes
3) threat of war/coming of war
The resulting influx of European artists stimulated American painters (especially the young) leading to Geometric Abstraction and Surrealism.
For the first time, American artists could (without traveling half-way around the world):
1) see works in depth
2) talk with painters
3) study under painters
Composition in Red, Yellow and Blue (Mondrian)
abstract artists
Josef Albers
Hans Hofmann
Piet Mondrian