County Vote Spinogram (Dem 2PV), 2008 by David B. Sparks.

Election Infographics: The top 1% of visualizations (and the bottom 47%)

If you’re reading this article, you’re probably no stranger to the red-and-blue electoral map, a fixture of every online news site (a sample of these maps can be seen here). These maps certainly get the job done, but suffer from low data-density–yes, they tell us the way that an entire state voted, but what if we want more detailed information? About counties, for instance? Mark Newman, of the University of Michigan, has created an excellent series of maps that progress in detail from state, to county, to county with shades of blue and red. He then resizes each map in proportion to population to create a cartogram:

A cartogram is a map in which the sizes of states are rescaled according to their population. That is, states are drawn with size proportional not to their acreage but to the number of their inhabitants, states with more people appearing larger than states with fewer, regardless of their actual area on the ground. On such a map, for example, the state of Rhode Island, with its 1.1 million inhabitants, would appear about twice the size of Wyoming, which has half a million, even though Wyoming has 60 times the acreage of Rhode Island.

David Sparks, creator of the Marimekko plots on the previous page, takes the increase in resolution one step further by extrapolating isarithmic maps from county election data.

The granularity of these county level results led me to wonder whether it would be possible to develop an isarithmic map of presidential voting using the same data. Isarithmic maps are essentially topographic or contour maps, wherein a third variable is represented in two dimensions by color, or by contour lines, indicating gradations. I had never seen such a map depicting political data — certainly not election returns, and thus sought to create them.

First, it does a good job of depicting local “peaks” and “valleys” of partisan support clustered around urban areas. In the 2008 map, for example, Salt Lake City, Denver, Chicago, Miami, Memphis, and many other cities stand apart from their surrounding environs, highlighted by a relatively intense concentration of voters with distinct partisan leanings. In 1980, this method shows that though Reagan enjoyed broad support in California, the revolution was not felt in the Bay Area.

Sparks created an animation of these isarithmic maps from 1920 to 2008 to show the way that voting patterns have changed in the 20th century. While it would be nice to see a few major cities marked on the map for reference, this animation is so much more effective at showing transition than maps in which state or county lines are filled in, because the animation is constant and the resolution is so fine-grained.

Speaking of nationwide change, one more map from the New York Times sums up the remarkable redshift seen in the 2010 midterm elections. In this map, arrows are used instead fill, and instead of varying the shade of red or blue to indicate percentage change, the length of the arrow grows and shrinks. In the end, it’s a highly effective way of illustrating sea change elections.

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