As you can see by this graph, the poor income growth of the bottom 60% of Americans can largely be associated with these American's having never recovered from the recession of the 1990s and then stagnation and decline over the Bush administration; and, while I'm sure many Democrats will disagree with me, by the time the influence of the Obama administration is over they will (likely) be in a worse position that they were before Regan was elected.
The reason for this is simple, we no longer live in the economy of the 1940s, 1950s and 1960s and a high-school education with no skills beyond that will not get you a career that pays well; and being a high-school drop-out pretty much ensures that you will be unemployeed or work in a menial career. Those individuals who have gone onto trade-school or university and gained skills in in-demand fields (the top 20% of wage earners) are doing great; those that got skills in the liberal arts or other fields with limited demand (the second 20% of wage earners) are holding their own; but the bottom 60% are being failed by an educational system which is obsolete.
