www.americanprogressaction.org/issues/labor/news/2013/09/20/74751/middle-classes-are-stronger-in-states-with-greater-union-membership/
"Data on state household incomes released yesterday by the U.S. Census Bureau illustrate once again just how critical unions are in building a strong middle class, as states with greater union membership continued to have more robust middle classes than those with lower union membership in 2012."
