Bringing the nation back together is going to be very difficult. The main reason is, as you point out, that there is so few real interacdtions across the divide. Each side now has pretty fixed stereotypes of what the people in the other group are like (deplorables). Few people are having any decent conversations.
Also, they get their news and views from different sources. Trump has worked to make that worse. Why the Republicians let him go free range for a year I don’t quite understand. But now most “mainstream” newspapers are going through his past, and finding very upsetting things. But right-wing radio, and Fox News have been pushing conspiracy theories for two decades. It’s amazing how quickly it has shfited from Obama never leaaving office and imposing Sharia Law to Clinton now doing it. It’s like all of the people who are waiting for the end of the world.
How do we convince people that we are “One Nation?” Especially now that we can’t even agree if we are “under God.”