“According to Bishop, the author of The Big Sort, in 1976 less than 25% of Americans lived in places where the presidential election was a landslide. In other words, we lived next door to and attended school and worshiped with people who held different beliefs than ours. We were ideologically diverse. In contrast, in 2016, 80% of U.S. counties gave either Donald Trump or Hillary Clinton a landslide victory. Most of us no longer even live near people who are all that different from us in terms of political and social beliefs.”