According to this, incomes for the lowest four quintiles grow faster during Democratic administrations. I wonder if this has implications on the "both parties are essentially the same" argument.
I sent the first graph to a friend and he replied "Republicans must be better for income." That is clearly the opposite of what it says, so I tried to figure out how he misread it. I think he thought the x axis was time and the y axis was total growth. But it isn't. The income quintiles are in the x axis and percentage growth is the y.
Interestingly the income growth for the highest earners is the same in Democratic and Republican administrations. I guess they have it all locked up.