It was noted in this interview that most of the highest income ZIP codes in the country surround areas with large federal infrastructure: http://www.npr.org/20

It was noted in this interview that most of the highest income ZIP codes in the country surround areas with large federal infrastructure: http://www.npr.org/2011/09/06/140056904/the-top-secret-america-created-after-9-11 http://www.npr.org/2011/09/06/140056904/the-top-secret-ameri...