Mapping the political change in America

US presidential election results (© 2008 Mark Newman)
US presidential election results at county level (© 2008 Mark Newman)

John Carter Wood of Salacious Puddings fame has this morning posted and discussed two of a series of electoral maps published by the New York Times under the subheading “Voting shifts”. These display the change in presidential election results at county level compared with previous polls, and on first glance they appear to show a huge swing to the Democrats.

While undoubtedly useful, these two maps are potentially misleading. They do show the swing to the Democrats, but the results say little about the underlying politics of the US at local level. Mark Newman’s maps on the University of Michigan website (to which John links) are more informative. Why has it taken a physicist to provide the best psephological analysis of the election so far? The professional political pundits appear to me making it up as they go along.

The cartogram produced by Newman which accompanies this post employs a variable colour scale to show voting patterns at county level, with the map as a whole weighted according to the number of electoral college votes in each state (i.e., population level). The colours range from red, for 70% Republican or more, to blue for 70% Democrat or more. Mark has done an excellent job in visually representing the current state of political opinion in America. This ain’t no revolution.

While watching the election results come in the other night, I was wishing for such a county-by-county map. Obama won by a landslide in terms of electoral college votes, but with just a five point lead in the popular vote. That gives him a clear enough mandate to lead the country, but let it not be forgotten that the ideological scales in America remain fairly evenly balanced.

Looking at the sea of red in his second New York Times map, John CW concludes that there is a high density of plumbers in the south. He may have a point. I have heard a resident of Cambridge Massachusetts complain that they could never find a plumber when they really needed one.

There is talk of suspicious voting patterns in Alaska (also discussed here).