That spring, after all, Bishop had published The Big Sort: Why the Clustering of Like-Minded America Is Tearing Us Apart. It put hard numbers and gave a catchy name to something people from coast to coast already were feeling: Americans were getting more and more divided — sorted, as it were, based on income, occupation and education, religion, lifestyle and worldviews. And that in turn was having drastic political implications.

The statistics backed him up. In 1976, 26.8 percent of voters lived in “landslide” counties — counties, that is, in which the winner in the presidential election won by more than 20 percent. In 1996, it was 42.1, and by 2004, it was nearing half. “Americans are increasingly unlikely to find themselves in mixed political company,” Bishop wrote — “pockets of like-minded citizens that have become so ideologically inbred,” as he put it, “that we don’t know, can’t understand, and can barely conceive of ‘those people’” who lived differently, thought differently, voted differently. People weren’t picking presidents — they were choosing sides.

At a moment when the country is contending with its bitterest and most intractable issues — reproductive rights and gun control — I called Bishop for his perspective on whether Americans are in any better shape to overcome the crippling tribalism he documented 14 years ago. He was not encouraging.