How economic segregation helped inequality lose its salience:
Vigdor's theory of relative income predicts that the more income inequality there is in a geographic area, the more support there will be for redistribution among the poor and among the rich who are altruistic. The idea is that when a poor person looks around and sees rich people, she is more inclined to support redistribution than if she looks around and sees only poor people. When an altruistic rich person encounters lots of poor people, she will be more likely to support redistribution than if she only comes across other rich people. Among the working and middle classes, support depends on how many rich people there are, how many poor people, and how altruistic voters are. With more rich people, for instance, the working and middle classes will support redistribution because they will benefit. When Vigdor estimates the key “parameters” in his mathematical model using statistics, he finds that the estimates are consistent with these predictions.
An implication of Vigdor's findings is that one reason support for the Democratic Party among the working and middle classes failed to increase more as inequality grew is that segregation between the rich and everyone else has been on the rise for several decades. That means that today, the poor and the working and middle classes are less likely to see rich people when they look around than they were in, say, the 1960s.
Put another way, unless you can see the rich, you don't know you're poor. And unless you know you're poor, you're unlikely to demand that the government step in and help you out. There's a secondary possibility here that's also fascinating: In economically similar areas, stores will have settled and channels will have developed to allow the particular residents of that area to get by. As such, it could be that poverty in an economically mixed area actually generates a greater level of material deprivation than poverty in an impoverished area where targeted support systems, informal economies, and new norms have arisen.