It is a common argument that American government is run in the interests of rich people. But Eric Brunner, Stephen L. Ross and Ebonya Washington are in this month’s AEA Economic Policy journal with a different perspective:
We assemble a novel dataset of matched legislative and constituent votes and demonstrate that less income does not mean less representation. We show: (i) The opinions of high- and low-income voters are highly correlated; the legislator’s vote often reflects the desire of both. (ii) What differences in representation by income exist vary by legislator party. Republicans more often vote the will of their higher income over their lower income constituents; Democratic legislators do the reverse. (iii) Differences in representation by income are largely explained by the correlation between constituent income and party affiliation.
Here is one version of the paper (pdf).