Yeah, I saw that too.
Correct me if I’m wrong here on so something else I see: that the graphs show the lower class remaing somewhat constant while middle and upper class together have expanded as population has grown. That would seem to be evidence of upward mobility, showing middle class moving to the lower end of upper class, while lower class is moving into the lower end of middle class.
But at a quick glance the graph doesn’t appear to show that, since it juxtaposes middle class on one side against combined upper and lower class on the other.
They also extend the ‘middle’ class up to $126K. That may be accurate in urban areas, but such a family would be rich out in the boondocks. So maybe there are more upper-class and fewer middle-class households than they suppose.