I Have A Theory

That's a testable hypothesis and interesting. It might be that voting patterns are affected by so-called "identity groups" within which a person is connected and out of which some portion of their basic worldview is created. One's interest in the Red Sox could cause them to vote Democratic, not because there is necessarily some causal relationship between watching sports and voting, but because of these deeper peer effects. To test this empirically, you'd need to find individual-level data so that you could control for a variety of other variables that seem to affect one's voting preferences like religious background, income, gender, and race. You'd also want to get voting history. You'd also want to get data on various regional variables, like unemployment rate in your state, concentration of manufacturing in your state, etc. And finally, you'd want to find some reasonable measure of these socio-cultural variables you're describing - like how many CDs did you buy the past month, what magazines do you subscribe to, how often do you watch ESPN each week, favorite sports teams, etc. What you would need to think about, though, is whether or not there could be spurious correlations between sports interest and voting behavior. For isntance, residents of Boston might both be Red Sox fans and vote Democrat, but they don't (most likely) vote Dem because of their love of the Red Sox. The town is overwhelmingly liberal in its politics, and if you could not control for these kinds of local characteristics that are correlated both with sports and voting, you'll end up with sports picking up more effect than it should. In theory, that's easy enough to do (correcting for that kind of bias, that is). I think political scientists have studied the effect of things like culture on voting, because I seem to remember them looking at things like magazine subscriptions to determine whether it had an effect. But I have never heard about sports, and it does sound plausible. It's an interesting idea - I'll peek around and see what has been done, if anything, on it.

Also, I think there is clearly some kind of relationship between sports and voting, because of the publicity that NASCAR dads got this last cycle. It sounds like it's becoming apparent that some kind of relationship exists there - whether it's NASCAR driving voting, or whether something else drives both, is another question, but it seems like your intuition has some merit.