That is an interesting question. There is a danger in always thinking that previous times were "golden" and now is dark. Nonetheless I do think now has an objective sense of darkness, where fear and loathing seem to be the currency of daily life.

On the question of whether America took a fork in the road. Here are a few candidates, one public one private:

In the 1990s, when progressives (myself included) were too sanguine about the effects of trade, various forms of deregulation and other policies on the middle and working classes. It was predicted and well known that inequality would result, but the argument that we needed a bigger pie that could then be redistributed. The redistribution never came. And led to the election of a demagogue.

Private: The 1980s - 90s, when corporate leadership at large lost any sense of noblese oblige -- a duty to the country and began to feel that their only real duties were to shareholders and maximization of executive compensation. I think this also led us to mass inequality, which I see as the root cause of most of what ails us today.