Below we plot the first dimension DW-NOMINATE Common Space scores of the presidents in the post-war period, which we refer to as the “presidential square wave” due to its shape. An ideological score is estimated for each president throughout the entirety of their tenure in office by scaling their “votes” on a subset of roll calls on which they announce a position (measured using CQ Presidential Support Votes). Negative CS DW-NOMINATE scores indicate greater liberalism and positive scores indicate greater conservatism. The presidential scores are directly comparable across time and with members of Congress. However, there was a significant second dimension dealing with Civil Rights that lasted into the early 1990s. This will affect the first dimension scores of Presidents prior to George H. W. Bush.

These presidential CS DW-NOMINATE scores are estimated using all available CQ presidential support roll calls through 2015.

Very little has changed from the last presidential square wave. President Obama fits the spatial model estimated by CS DW-NOMINATE extremely well, with over 95% of his 803 “votes” correctly classified. Obama has moved very slightly rightward (-0.354) and is now just to the left of LBJ (-0.337) and right of Truman (-0.373), though this trio is virtually ideologically indistinguishable. President Eisenhower is the most moderate president (0.282) of the post-war era.

Among members of the 113th Congress, President Obama is very ideologically close to Representatives Stephen Lynch (D-MA) [-0.355] and Marcy Kaptur (D-OH) [-0.352] in the House, and Senators Charles Schumer (D-NY) [-0.350] and Mark Udall (D-CO) [-0.353] in the Senate.

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