I’ve been reading through the new Pew report (pdf) on this question. I found these to be the two most interesting passages:
As the middle-income population hovers near minority status, the population of upper-income adults is growing more rapidly than the population of lower-income adults. From 1971 to 2015, the number of adults in upper-income households increased from 18.4 million to 51 million, a gain of 177%. During the same period, the number of adults in lower -income households increased from 33.2 million to 70.3 million, a gain of 112%.
I would say America is developing its top twenty percent rather nicely. The future refrain will have to be: “We are the eighty percent!”, or something like that. Then there is this:
The biggest winners since 1971 are people 65 and older. This age group was the only one that hada smaller share in the lower-income tier in 2015 than in 1971. Not coincidentally, the poverty rate among people 65 and older fell from 24.6% in 1970 to 10% in 2014. Evidence shows that rising Social Security benefits have played a key role in improving the economic status of older adults. The youngest adults, ages 18 to 29, are among the notable losers with a significant rise in their share in the lower-income tiers.
That part augurs not so well for our future, given a certain degree of persistence of earnings.
I was part of an NPR On Point discussion of the study.