For further reading:
The Brookings Institution put Boston at the top of its list of cities with the greatest income inequality:
Wealth Divides: Exploring the stark dividing lines between rich and poor in American cities
Income inequality in the United States
https://en.wikipedia.org/wiki/Income_inequality_in_the_United_States
Causes of income inequality in the United States
https://en.wikipedia.org/wiki/Causes_of_income_inequality_in_the_United_States
Inequality.org: Income Inequality
http://inequality.org/income-inequality/
Pew research Center: Income Inequality
http://www.pewresearch.org/topics/income-inequality/
Britannica On-Line: Income Inequality
http://academic.eb.com/levels/collegiate/article/627100
US Census -- Income Inequality
http://www.census.gov/topics/income-poverty/income-inequality.html
U.S. Census : Measuring Income Inequality, Metrics
http://www.census.gov/topics/income-poverty/income-inequality/about/metrics.html