When did America's divisiveness start?

I've been thinking a lot about the recent state of affairs in the US.

This came to a head the other day when I felt like I was unfairly attacked for an opinion I shared on Facebook, though the topic doesn't matter so much.

I was thinking about Trump who, in some respects, I view as a reaction to Obama....who was a reaction to Bush and so on.

I went all the way back to 1991.

End of the Cold War.

I have a friend in Israel, Anat, who said to me once "the big joke here for the Arabs is that they don't realize that if they just left us all alone, we would kill each other."

There is something about having an external enemy that unites people. 

With the end of the Soviet Union, the USA became the "sole superpower" as we here so often.

But, I wonder if that lack of an external enemy led the country down a path where people started turning against each other?

First, gradually, then, accelerated by the Internet and Social Media, in greater swings.

Just a thought.

Probably a lot more here, but that's all for now.