Why is it considered rude to talk about politics in the midwest? Is it because they are trying to hide the fact that they actually don't know anything about politics?
I've lived in the midwest my whole life, people talk about politics.
Something about the midwest that outsiders don't really understand is that people try not to step on other peoples toes. If you're aggressively pushing your political beliefs, you're going to get a bad reaction (even if it wouldn't seem aggressive on the coasts). If people are not wanting to talk to you about politics, it could be because you're ignoring cultural cues and acting like an aggressive jerk.
The same stigma exists in the south. Religion is also typically among the "taboo" topics.
The real reason is because politics and religion are both topics that tend to get people angry at one another. Just look at this board for evidence of how petty and immature adults can get when talking politics.