Here is a direct link to the “study” mentioned in Dave’s article.
It was released three days ago and showed the reduction of people having “mixed” political views from 1994 until today.
More people claim the other side is a “threat to the nation” which accounts for the acrimony we are seeing.
The Republican (and to a lesser extent Democratic - sorry but true) leadership in Congress is forcing party line votes leading to less and less bills being passed although the world is changing faster than ever.
My sense is that if the dynamic plot given above were just of Congressional members, there would be very little overlap (far less than the population as a whole driven by party line demands) which accounts for the lack of progress (bills passed) which is exactly what corporate America and some conservatives want.