Nathan, Torie, and bgwah make sound points. The issue involves a complex set of demographic variables, as the following graphs show:
Whites without high school degrees are less Republican than white high school graduates, but in each education category beyond that, voters are more Democratic. Richer people within any education category are more likely to vote Republican.
Interesting that poor post grads are even more reliably Dem than the poor w/o HS. Presumably the rural poor shift enough away from the urban poor to make that so. I'm guessing that the income axis is simply the five quintiles.
I'v always thought that one of the most uber-Dem demographics was low-income highly educated people.
