Ok, I'm not one who buys into the notion of, "Gee, we used to be the good guys." IMO, the US has always been rather ruthless and heavily pragmatic, be it Indian removal or waiting until the last minute to fight Nazis. But, there is something here that I am sure has changed over the past 50 years. Our collective agreement on what and who we are has changed radically.
In short, I believe we are more divided now than ever. Even on the most basic American principles, we can no longer agree. And, the radicals, be they Left or Right, authoritarian or anarchist, are more the majority among us now than the exception.
When I was young, it seemed to me that most of us were, if not on the same page, at least reading from the same book. Today, we aren't even in the same library. Back then only the nuttiest of nuts denied the effectiveness of vaccines, refused to accept the basic tenets of evolution, thought the universe wasn't billions of years old, believed that the earth was not round and sphere-like, or considered the Bill of Rights to be more an obstacle than something to rally behind. Today, all those things are up for debate, and tens of millions of people buy into them, vigorously.
What the hell happened?