Riffing on the blogosophere’s many riffs on this wonderful Robert Samuelson column in which it is explained that

the poor and middle class do have powerful advocates. To name three: the AARP for retirees; the AFL-CIO for unionized workers; the Center on Budget and Policy Priorities for the poor.

we find Drum noting

The top 400 taxpayers, a group so rich and elite that I’d need scientific notation to properly represent their proportion of the population, have doubled their share of income in the past decade or two but have decreased their tax burden by nearly half. Nice work! As you can see, Warren Buffett wasn’t exaggerating when he said his secretary paid a higher tax rate than he does.

Which refers to one of the most remarkable trends of recent history, of which Lane Kenworthy has the best graph, in which incomes shown “include government transfers and subtract taxes”:

There’s some discussion over which comes first, the political polarization of recent years or the income polarization of recent years. Krugman says [in the pdf linked here] “it looks as though the political polarization is the lead on the economic changes”—which is to say, people don’t vote Republican/Democrat because they’re rich/poor, rather, the rich have gotten richer because of Republican policies.