The ultimate political networks graph

James Moody and Peter Mucha presented some of their recent research on party polarization at the most recent political networks conference at Duke this past spring.  Their presentation included the following graph, which uses agreement scores between members of the U.S. Senate to demonstrate polarization over time.  As the graph suggests, polarization in the Senate is at near historic levels, although there was a slight increase in cross-partisan agreement during Bush's second term.

Regardless, the graph is extremely cool.  (h/t Jennifer Victor)