Please note these are household incomes they are referring to below:
"The middle-middle class may be composed of those households with annual incomes of 80% to 120% of the national median household income. Persons in this income range could, in accordance to solely economic reasoning, be referred to as the American average. Such households would boast annual incomes ranging from $35,200 to $52,800, and thus be located in the middle of the income range. Some of these households, while actually being in the middle and thus sometimes referred to as being middle class, cannot, however, afford the middle class lifestyle."
American middle class - Wikipedia, the free encyclopedia