In a process that had begun in the 1980s and suddenly...

In a process that had begun in the 1980s and suddenly accelerated in the early 2000s ... [t]he peaks of great wealth grew higher, rising up beyond the clouds, while the valleys of poverty sank lower into perpetual shadow. The once broad plateau of the middle class eroded away into a narrow ledge, with the white-knuckled occupants holding on for dear life.