I think a return to having a tightly connected neighborhood would do the US a lot of good. People may pay more attention to what's happening in their town and local politics which could help change things from the ground up.
Most importantly though, I think tighter neighborhoods would help people see those they don't agree with as actual people with more in common with them than not. As Thomas Jefferson said, "I never considered a difference of opinion in politics, in religion, in philosophy, as cause for withdrawing from a friend."
As an aside, I have been thinking about how much I would love to be able to buy an empty lot in my neighborhood to open it up as a community space to bring people together outside of social networks.