Honey, I shrunk the middle class
story, it seems it's basically wages between 35 and 100k per year. At any rate, less jobs in manufacturing and more in services, particularly in health jobs, like nurses. Also, a gender bias, with an increase in female participation in the middle income jobs. And yes, increasingly these jobs require a college education. So more nurses and less machine operators, or something like that. The problem is that with this the size of the middle class is effectively shrinking (see graph below).