Video: The History of American Politics in Two Minutes

Below we use DW-NOMINATE scores to illustrate the ideological composition of each Congress (1st to the current 112th) in the following video. The first dimension (the horizontal or x-axis) represents placement along the familiar liberal-conservative spectrum; the second dimension represents different issues which have divided the parties over time (e.g., race in the mid-twentieth century). Note the trends in political polarization (namely, how the two parties have become more internally cohesive and distant from one another) seen over the last thirty years.