200 years ago Alexis de Tocqueville wrote about the exceptional ability of Americans to cooperate in solving problems that required concerted collective action. This capacity for cooperation apparently lasted into the post-World War II era, but numerous indicators suggest that during the last 3-4 decades it has been unraveling.
(This text from Peter Turchin is from 2013, but I think it is still relevant, not only for what's going on in the US)
In particular, over the last two decades that situation has seriously deteriorated, and only keep getting worse day by day. Identity politics in my country have never been more popular than they are now.
That's when the big, large "we" of civil society disintegrated into dozens, even hundreds of little, tribal "we's".