What are the motifs in The Hidden Dimension by Edward T. Hall?

Throughout the world, people of very diverse cultures are now coming together to live and work. Nowhere is this more evident than in the United States, traditionally been termed the "melting pot" of all cultural groups. This "melting pot" does not really occurred, however, because, as ethnic and cultural groups arrive in American cities, they tend to congregate in enclaves, in which their specific spatial perceptions and needs can be somewhat honored.