Between 1989 and 2011, the average income of [Massachusetts’s] top fifth of households jumped 17 percent. The middle fifth’s income dropped 2 percent, and the bottom fifth’s fell 9 percent. Massachusetts now has one of the widest chasms between rich and poor in America: It is the seventh-most unequal of the 50 states, according to a Reuters ranking of income inequality. Two decades ago, it placed 23rd. If the great equalizer’s ability to equalize America is dwindling, it’s not because education is growing less important in the modern economy. Paradoxically, it’s precisely because schooling is now even more important.