This Brookings research by Gary Burtless reveals lessons about changes in incomes in the U.S. that may be surprising to some. These changes relate to quintiles of the distribution, NOT to migration of individuals across quintiles. The data do not show stagnation in the middle and lower end of the income distribution. Non-cash sources of income have grown rapidly relative to total income. The changes show that income at the top is quite volatile, and income at the low end has been insulated from shocks by transfer payments. 

Redistributionists should love this data in many ways, but I suspect this information will be passed over by the left to avoid diluting their message that more redistribution is needed to achieve social justice…  always more.