Robert D. Putnam, Our Kids: The American Dream in Crisis, Chapter 1.

Chad Stone, Danilo Trisi, Arloc Sherman, and Brandon DeBot, A Guide to Statistics on Historical Trends in Income Inequality (Center on Budget and Policy Priorities, Washington, D.C., 2015). pp. 1, 7-19.

Just for fun:

Leslie McCall and Christine Percheski, “Income Inequality: New Trends and Research Directions,” Annual Review of Sociology 36 (2010): 329-347.

Jacob Hacker, “The Privatization of Risk and the Growing Economic Insecurity of Americans,” The Privatization of Risk Web Forum, Social Science Research Council (2006).

Kendra Bischoff and Sean F. Reardon, “Residential Segregation by Income, 1970- 2009,” Diversity and Disparities: America Enters a New Century, John Logan (ed.) (Russell Sage, 2014) :