Beautiful Data

Example 5: Localized Partisanship in Pennsylvania

In 1986, political strategist James Carville, who later ran Bill Clinton's first presidential campaign, described Pennsylvania as Paoli and Penn Hills with Alabama in between. Paoli is a suburb of Philadelphia, and Penn Hills is a suburb of Pittsburgh, and so Carville was referring to the two urban centers of this long-standing "swing state" as Democratic strongholds, with the remaining rural areas of the state as Republican territory.

Carville's words are indicative of the broader desire of both the public and the highest level of political punditry to divide the country into red and blue areas. For most Americans with an even passing familiarity with elections in the 21st century, one of the defining images of recent American politics has been the ubiquitous electoral map from 2000 and 2004, featuring slivers of blue states along the north and west coast, and a sea of red states in the south and the heartland. Despite President-elect Barack Obama's insistence that we are not a collection of red and blue states, this salient imagery is difficult to overcome.

Figure 19-5 presents a clarification of sorts for Carville's description of Pennsylvania and a different way of looking at geographic partisanship, based on a new and exciting type of data and a rich visualization technique. The bottom layer of the map shows Pennsylvania counties shaded by their 2004 presidential election returns, with blue indicating higher support for the Democratic ...