Y'all knew I couldn't stay quiet, right?
The advantage of old age is that you have a yardstick to measure many things by, one of which is comparisons of decency, manners, public attitudes, etc, etc.
Speaking for myself, of course, I look back to 1967 when I arrived in the US, and run a video in my mind of all the changes I've experienced, with JFKs assassination being a milestone, and the Vietnam War standing out as the first of many mistakes by many forthcoming Politicians up to the present.
I really believe that the years between 1945 and 1963 were the most tranquil and quiet in this country, with the Bay of Pigs an exception, and up till then a modicum of civility and good feeling was being experienced by much of the Public. Generally, a feeling of "The good ol' USA can do no wrong!" prevailed. It seemed to be generally accepted that we were the good guys, and our system was the best in the World. Then came Tricky Dicky, Elvis, and Joe McCarthy, and the USA started to change.
I don't mean this as a History Lesson, just as personal feelings of the changes I've seen. Sure, there were many wrong things going on then, but generally I think Americans felt happier, more secure, and content with their leaders compared to now. Watching some (not all, my stomach won't take it!) of the Republican and Democrat Conventions, I can't believe the vitriol and viciousness of the speakers on both sides. This wasn't what I came from England to enjoy, even though my Mother Country has had its share of unhappiness in various ways.
To wrap up, perhaps Democracies can only last approximately 300yrs before imploding, just like the Roman Empire, and we are fated to start all over again!