In reference to the Red State Blue State project that Andrew Gelman and I are working on, he writes,
As we’ve discussed before, the Republican party gets more support from the rich than from the poor, especially in poor states. (In poor states such as Mississipi, rich people are much more Republican than poor people; in rich states such as Connecticut, rich people are only slightly more Republican than the poor.)
Rich voter, poor voter
The next step is to look at time trends. Here we use the National Election Studies pooled into 20-year intervals. First, the difference between rich and poor voters in rich, middle-income, and poor states. As you can see, the gap in voting between rich and poor voters has increased, but especially in the poor states: