A question from Yahoo! Answers:
What are some trends in inequality in the U.S.A in the past 40 years?
Inequality has bottomed out in early 1970s and has been on the rise since. It has been estimated that 1% of wealthiest households held about 18% of the aggregate U.S. wealth in 1974; by 2000, the percentage has increased to approximately 40%.
(The graph above is borrowed from Robber Barons by J. Bradford DeLong)