If you find yourself 10 miles north of New York, you'll be in leafy Westchester. Do the same in Paris, and you're in the banlieue Saint-Denis.

Many European central cities have retained their wealth, leaving the suburbs to poorer citizens, while beginning in the 19th century and continuing throughout the 20th century, US central cities suffered economically from suburban flight. Of course, things are changing, but I'm interested in why this happened, particularly a propos the intellectual history of planning in both societies.

What are the origins of this phenomenon, especially in comparative terms? Has the French upper class, for example, have the same aversion to cities as Americans /purportedly/ do? Do multiple national planning philosophies crop up in Europe, according to each country?

Thanks