Regarding the Chicago map, I need to note that it divided up the income spectrum in a pretty weird way.
Typically, income quintiles are based 20% of households. Therefore, the bottom 20% are the poorest 20%, the middle 20% are the middle 20%, etc.
However, the categories shown here don't track. The "middle class" is defined as being those within 20% of the (national?) average.
The problem with the amount of people within this group won't necessarily be 20%, and likely shrunk over time. Over the last few decades, the top quintile (as defined by normal standards) has really pulled away in terms of income:
Note that although there's a lot of focus on the upper class typically - the 1%, the increase is not limited to this group. Everyone upper-middle class has done well, more recently.
What does this mean? In absolute numbers, there are probably way more people making more than 40% more than the median household nationwide. So as much as the Chicago maps capture a real trend, it's likely overstated a bit, just because there's more top-end wealth in general.