This expertly opinion by Yascha Mounk is published by The Atlantic. Here is an excerpt:
Until a few decades ago, most Democrats did not hate Republicans, and most Republicans did not hate Democrats. Very few Americans thought the policies of the other side were a threat to the country or worried about their child marrying a spouse who belonged to a different political party.
All of that has changed. A 2016 survey found that 60 percent of Democrats and 63 percent of Republicans would now balk at their child’s marrying a supporter of a different political party. In the run-up to the 2020 presidential election, the Pew Research Center reported that roughly nine out of 10 supporters of Joe Biden and of Donald Trump alike were convinced that a victory by their opponent would cause “lasting harm” to the United States.
As someone who lived in many countries—including Germany, Italy, France, and the United Kingdom—before coming to the United States, I have long had the sense that American levels of partisan animosity were exceptionally high. Although I’d seen animosity between left and right in other nations, their hatred never felt so personal or intense as in the U.S.