New Viz: The Widening Gap – Political Polarity in the US

I was born in 1976 and, in those 44 years, I cannot recall ever seeing the United States so politically polarized. It’s disconcerting and a bit scary. I’ve even heard and read people talking of the need for a second civil war!! I’m sure that’s just hyperbole, but it’s worrisome, nonetheless. But, as I thought about it, I began to wonder if it’s really as bad as it seems. Perhaps it has been worse at other times in our history??

To understand the historical polarity of our two major parties—Republicans and Democrats—I decided to find some data and visualize it. The data I used came from and leverages DW-NOMINATE scores. This procedure was first developed by Keith Poole and Howard Rosenthal in the 1980s and is a multidimensional scaling technique that uses various data to score legislators’ ideological positions (i.e. liberal/conservative or left/right). The scores assigned run from -1 (far left/liberal) to +1 (far right/conservative). Using data back to the 25th Congress (1837 – 1839), I visualized the trends over time and attempted to analyzed those findings.

To view the interactive viz, click on the image below.

Ken Flerlage, September 16, 2020


  1. Awesome analysis and very timely! Hope this election will start to narrow the gap...we need it!


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