https://realisticobserver.blogspot.com/2017/09/in-case-you-missed-this-antia-planning.html#more The 2016 election demonstrated what has long been been bubbling beneath the surface and finally erupted like Mt. Etna--the present two party elite dominated system has failed the American electorate. The emergence of the TEA party movement was the beginning of the overt anger that many felt against the GOP establishment and continues its rebellion to this day.
On the Democrat side, mainstream Dems are beginning to fully realize that the left wing of their party is not on their side. Many are issuing wake up calls to the leadership, but the left seems to be in control, for now.
AntiFa is not just a leftist Democrat reaction to Trump's victory. It is has been around for a long time, and remains dormant until a perceived opportunity for action presents itself.