There are lots of high population density suburbs outside the United States. Two examples: http://en.wikipedia.org/wiki/Banlieue http://en.wikipedia.org/wiki/

There are lots of high population density suburbs outside the United States. Two examples: http://en.wikipedia.org/wiki/Banlieue http://en.wikipedia.org/wiki/Banlieue http://en.wikipedia.org/wiki/Million_Programme http://en.wikipedia.org/wiki/Million_Programme