Try to keep things in perspective. American politics has always been rough-and-tumble since the inception of the republic and the formation of feuding factions that became political parties -the period from the Great Depression through the beginning of the Reagan era was an exception to the rule. From the personal attacks between Adams and Jefferson, to the beating of Massachusetts Sen. Charles Sumner by South Carolina Rep. Preston Brooks, there has always been an element of violence and character assassination in our republic. We are merely returning to the norm.
Agreed. One unique factor in the period from the 1930's to 80's was the oligarchic control of the primary news media. First it was the four radio networks then the three tv networks. The rise of cable news and the internet returned the news media to the wealth of niche outlets that were common in the press before radio.
I think there are a lot of thoughtful answers here, including this one.
But I want to address the people who think the GOP and Democratic parties "have
not flipped" in the last 100 years or so.
You need to explain a couple of things, like why the Democrats' nominee this year is assured of winning practically none of the states that the party's nominee won in 1896:
And why the two closest elections of the 20th century, 1916 and 2000, produced mirror images:
[modify:] To make it simple, there were only seven states of 48 that voted the same way in 2000 as they had in 1916: Democratic: Washington, California, New Mexico, and Maryland; Republican: South Dakota, Indiana, and West Virginia.