In liberal strongholds (like SF, where I live), many conservatives will hide their political views for fear of social alienation. I've experienced this directly, when someone I'd recently met sort of sheepishly/obliquely brought up that they supported Trump. That fear is warranted: I really had less interest in developing a closer friendship with that person after learning that. It was especially jarring to me that this person was a non-white woman, and I just cannot understand how someone can support someone whose rhetoric demeans her on two axes.

I expect the same happens in conservative strongholds too, with liberals self-censoring. I know I wouldn't be comfortable openly discussing my (leftist) political views in, say, suburban Texas.