Politically, I believe a major factor in our divisiveness has been a lack of cross-pollination with people who are different from us. People in the city stay in the city, and people in the country stay in the country. It's much easier to empathize with people in your "out-groups" when you know and interact with some of them personally.
Economically, while urban centers have been exploding, rural America has been rotting. There's no economic export bringing money to many areas. And without that, entire towns sink into economic decay. Rural America was built on manufacturing, because all it required was cheap land, and that's largely gone now. Imagine a world where cheap land is once again the deciding factor that draws economic activity, because high-income remote-workers are drawn to it and have no other constraints. And then those people spend lots of money in all those little economies.
Another aspect that's had a big impact on economic inequality is the growing cost-of-living gap. It's really hard to move to the city and seek a way upward in the world when you can't even hope to afford rent. Spreading out the white-collar jobs geographically could spread out the opportunity economically.