Overton window – not the actual politics shifting so much as our view of those politics has shifted – instead of sitting over a centrist position keeping both left-wing and right-wing in view, the American window is positioned over right-wing bringing far-right into the perception of being acceptable and moving left-wing into the perception of being extremist

On a global Geopolitical scale our(American) Left/Right perceptions have moved gradually right. What we consider the moderate right is closer to the far right in most other places. The same happens on the left. Our moderate left politicians are closer to the center of the scale, and the far left is more akin to liberal parties in other places.

The American scale has always been skewed this way, it’s not necessarily that it happened in the last 10-15 years, more that from the start it was shifted.