At the same time, American voters and political elites are more polarized than ever. Republicans and Democrats occupy not only their own ideological camps, but also their own sets of basic facts, regardless of whether those facts rooted in reality. American politics is trapped in a feedback loop that reinforces polarization in the mass public: media coverage of polarization increases citizens’ dislike of the opposite party, and new research shows that people go beyond relying on party cues as a cognitive shortcut: They consider partisanship a central part of their identity and put effort into expressing it. For example, evangelical Christians tend to identify as conservative Republicans, but recent work shows that partisans actually sort themselves into the religious affiliation that matches their politics.

There are no doubt many reasons for the rise of partisanship, but our research, using voting data from across the country over a four year period, recently uncovered an important one: the loss of local newspapers. As local newspapers disappear, citizens increasingly rely on national sources of political information, which emphasizes competition and conflict between the parties. Local newspapers, by contrast, serve as a central source of shared information, setting a common agenda. Readers of local newspapers feel more attached to their communities. Unless something is done, our politics will likely become ever more contentious and partisan as the media landscape consolidates and nationalizes.