The last map perfectly shows what's so depressing about US politics (poor people voting massively for a party dedicated to serve the interests of the wealthier).
However, it is generally the wealthy voters in each state which vote more Republican--it's just that poor people in, say, Kentucky, are more Republican than poor people in Connecticut.
The wealthy voters are more Republican, sure, but that doesn't mean that poor voters alone wouldn't carry the state for Republicans.
Kentucky 2008 exit poll, whites with income under $50k:
42% Obama
57% McCain
or, even worse, the same statistic for Mississippi:
16% Obama
84% McCain