Click here to access article by David Ruccio from Real-World Economics Review Blog.
The charts have been designed by an economist, and as such will require a bit of study to see some rather startling differences between two post-war periods. It appears that the dramatic changes in income by percentile groups radically changed after neo-conservatives took over leadership in the ruling class starting in 1981 under the Reagan administration which promoted reduced tax rates for the rich, attacked unions, promoted deregulation of the economy (sold as "trickle down economics"), and began the development of a police state infrastructure under the cover of the War on Drugs (see this, this, and this).
Liberals would like to view the social-economic events after 1979 as some kind of aberration in the system of capitalism. I see it in part as only a natural evolution in its dynamics which rewards only a tiny segment of the population--those who "own" all significant economic enterprises. But, I also see the rise of capitalist rightwing agendas as retaliation against the American populace for their opposition to the Vietnam War and their support of the Civil Rights Movement.