The Media Targeting Black Woman, You Should Be a Democrat?

As you point out in the book, people all have a lot of different overlapping identities. So why would it turn out that the media targeting all a persons different identities would end up pushing them towards one party? Like why would it be the case that the media targeted at ana ban black woman all line up in the direction of, you should be a democrat? This, to me, is the enabling function of the parties becoming themselves more polarized, because it created a clearer sense of what goes with what.