Interest to a broad audience. I want to frame, before we start, the significance, as we understand it for the study of american politics. This item was stationed describes modern american politics. Context was asian is multidimensional what you cannot deduce the politicians knowledge from tax policy. And then increasingly unidimensional. There is an ideological line. Concurrent with this, there has been an ideological sorting to a lesser extent, but notable in the attitudes of voters. A variety of lyrical dysfunction stems from partisan gridlock. The past couple of decades has produced a large and impressive body for polarization. Congressional behavior for average americans. For number of reasons that i think we will get into in other remarks and more detail, some of the findings from that literature have entered the conversation as among political journalists, the polarization has become go to framing for understanding the maladies of contemporary american politics. In the last two y