^True. Although the New York metro area can't be far behind in physical size. One of the better maps he drew compared the Pearl River Delta (Hong Kong, Macau, Shenzhen, Gaungzhou, Dongguan, etc.) - a megalopolis of 60 million people to Chicago, which has a metropolitan area of similar physical size. American cities are really in a league of their own, sprawlwise, and even the most compact of them - like the Bay Area - still make Canadian cities look good.
On the GTA map, there are some interesting discoveries as well. Hamilton is surprisingly compact, for one, with its 500,000 people crammed into an area about the same size as Oshawa-Whitby or Kitchener-Waterloo.