The US Census Bureau defines lower class as the lowest 20% of incomes.
Pew defines it as the lowest 2/3 of the median.
If the highest income is $100, 20% is $20.
At 2/3 the median, if the median is $30, lower-class is $20.
Is there a reason they’re tying income classes to people within those classes, and not what it costs to survive within the economy?


It seems to me like you are coming to grips with the fact that statistics are nice but one mustn’t trust those one hasn’t forged personally.
I imagine there may be political or even practical reasons why they draw the line there. A lot of times lines remain fixed because they made more sense when they were drawn ages ago and now it’s just a pain in the butt to change them. Or to keep numbers comparable with those from previous years.
Or maybe there are laws or regulations that would be triggered if you move the goal post. If you start reporting the number of poor people or their income in a different way, that could affect government spending. If that’s the case, there could be a lot of friction in trying to update the calculations.