Thanks for pointing this out. I wasn't actually aware of the consistency of this shift over time. I didn't love this graph, however, so I went looking and found

Thanks for pointing this out. I wasn't actually aware of the consistency of this shift over time. I didn't love this graph, however, so I went looking and found far better displays (IMO) of this trend here: https://www.pewsocialtrends.org/2015/12/09/the-american-middle-class-is-losing-ground/ https://www.pewsocialtrends.org/2015/12/09/the-american-midd... In particular, the following is more informative and doesn't rely on a zoomed-in axis to emphasize the change over time: https://www.pewsocialtrends.org/wp-content/uploads/sites/3/2015/12/ST_2015-12-09_middle-class-03.png https://www.pewsocialtrends.org/wp-content/uploads/sites/3/2... It's also adjusted for household size: > In this report, “middle-income” households are defined as those with an income that is 67% to 200% (two-thirds to double) of the overall median household income, after incomes have been adjusted for household size.