Last I heard a middle class income is defined as 50,000.00 - 150,000.00 per year but that was a couple three years ago.
The median household income in the US is 59K. The term "middle class" is poorly defined and politicians like it that way. Politicians always talk about the middle class because most people think they are part of it. If you want to look at income distribution you need to look at the household income quintiles which start with the lowest 20% of the income distribution and move up 20% at a time from there. The middle class roughly includes some people in the second quintile (2015 mean income 33K), the third and fourth quintiles and people from the bottom of the fifth quintile (upper limit of the fourth quintile was 112K in 2015). So the middle class might include people with household incomes from 35K to 150K depending on where you live since living costs vary a lot by region.
