Yes, income inequality has risen dramatically over the past 35 years. But something else has happened that might surprise you. The size of the upper middle class is expanding, as Americans migrate up from the ranks of the middle class and poor, according to a new analysis from the Urban Institute. Economist Stephen J. Rose uncovered this finding by defining how much income families needed in 1979, just before inequality really took off, to be counted as rich, upper middle class, middle class, lower middle class, or poor. He anchored his class divisions largely around incomes relative to the federal poverty level. For example, he set the income floor for the upper middle class at five times the poverty lev…