Complex sentence: The World's Fair was a major turning point for the arts in Seattle, and the fact that its modern art exhibition far outdrew the Burlesque Hall represented an important societal change; local galleries and museums, however, were almost completely empty during the fair.
Split into simpler sentences: The World's Fair was a major turning point for the arts in Seattle, and the fact that its modern art exhibition far outdrew the Burlesque Hall represented an important societal change. Local galleries and museums, however, were almost completely empty during the fair.