In two of his Forbes columns, NYU's Thomas Cooley challenges – with data – the widespread misunderstanding that America's middle-class is disappearing. Here, and then here.
(HT Greg Mankiw) The Terry Fitzgerald work that Cooley mentions was mentioned here at the Cafe a while back.
I raise, though, one objection to Cooley's otherwise excellent columns. In the first one linked to above, he credits technological change for the explosive economic growth of the 1980s and 1990s. I don't accept technology as an explanation. A rush of technology has causes; it must be explained. Technology is not a variable exogenous to economic growth.