America has always had its divisions, and Americans have never really been a monolith. We’ve always been a nation of many nations. The culture of New England is different from the culture of the Deep South, which is different from the cultures in the West Coast or the Midwest. People living in the cities have different beliefs than people who live in the countryside. Within those areas, there are ethnic, linguistic, and religious enclaves. It’s always kind of been like that (probably to a lesser degree in the past), and somehow we’ve been able to find enough common ground to...