The world is undergoing a historical and cultural rupture. Just as Hollywood and other American exports once gave the rest of the world a glimpse of modern life and the future that awaited them, China is now doing the same for African, Latin American, and even American young people.

BERLIN—For much of the 20th century, the United States represented not just a place on the map. It was also a point in time. When Western Europeans looked at images of America after World War II—depictions of Hollywood’s glamor, American cars, and newfangled labor-saving devices—they thought they were looking into the future.