Did we really get wealthier? Find out.

An article (blog) by John Cassidy in the New Yorker painted a picture where in forty years time the annual income of the average American hasn't grown. Measure this to increased cost of living and the avaerage will have become poorer. (See:  Poverty and Income in America: The Four Lost Decades and NY Times Soaring Poverty Casts Spotlight on ‘Lost Decade’; Sabrina Tavernisse)
Some figures form these articles:
2.6 million people living under the poverty line, in US today (stated $ 22,314 in 2010)
Average household $ 49,445 (compare 1999: $ 53,252)

According to the Census figures, the median annual income for a male full-time, year-round worker in 2010 — $47,715 — was virtually unchanged, in 2010 dollars, from its level in 1973, when it was $49,065, said Sheldon Danziger, professor of public policy at the University of Michigan

Now, it is interesting to verify the data from the articles.
I used Datastream to globally check the trends the articles claim.
Method: Time series > charting > new chart.
Charting is fairly easy to use.
I rebased all data to 100 so I could present all data in a sigle chart.
The result from my search is shown underneath.

In a table (not rebased):