Why elections matter, in one graph

I've been trying to figure out how to link to Timothy Noah's series on inequality, which falls under the rubric of "things you should read that I have nothing to say about." One thing I can say is that Noah, Catherine Mulbrandon and Slate have put an enormous amount of work into creating visuals to accompany the articles, and the results are really impressive. This graph, for instance, is the best visualization I've seen of Larry Bartels’s striking data showing how different income groups do under Republican and Democratic presidents:

Much more here.