Income measures seem to tell a similar story, at least over the long term. In 1980, middle-income Americans accounted for 60 percent of the nation’s total income. The upper-income folks accounted for 30 percent of national income.
Over the next 30 years, middle America lost and upper America gained. In 2010, a new milestone was reached: upper income Americans accounted for a larger share of income than middle-income Americans. (Read more: The Falling Fortunes of the One Percent)
But here is an equally important fact: many of those middle class Americans became upper-income Americans. The rich did get richer, but they also became more numerous.
The study shows that as the number of middle-class Americans fell (from 61 percent of the population to 51 percent of the population), the percentage of Americans who are upper income surged from 14 percent of the population to 20 percent of the population.
According to Pew, the shrinking middle and rising top comes from two trends: “Larger income gains for upper-income households than for others and a decline in the share of adults who live in middle-income households,” as well as a growing “share of the adult population living in upper-income households.”
Granted, some of the middle class also fell lower on the ladder. But the majority of those who disappeared from the middle wound up at the top.
A majority of middle-class adults in the survey say they have a better standard of living now than their parents had at the same stage of life. A majority also say they expect their own children’s standard of living to eventually surpass their own.
And many more of the middle class say they grew up in the lower-middle or lower class (40 percent) than say they grew up in the upper-middle or upper class (16 percent); 44 percent say they grew up in the middle class.
I suspect the numbers for the upper class would also reflect this mobility – even if conventional wisdom today also tells us that mobility is dead.
Do you think the wealthy have gained at the expense of the middle class since 1980?
-By CNBC's Robert Frank
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