News Sharing on Social Media: Mapping the Ideology of News Media, Politicians, and the Mass Public

Abstract

This article examines the information sharing behavior of US politicians and the mass public by mapping the ideological sharing space of political news on social media. As data, we use the near-universal currency of online information exchange: web links. We introduce a methodological approach and statistical software to unify the measurement of ideology on social media platforms by using sharing data to jointly estimate the ideology of news media organizations, politicians, and the mass public. Empirically, we investigate the electoral incentives that members of Congress have to share ideologically polarizing information online. We show that the more competitive an election is, the less likely politicians are to share ideologically polarizing information. This finding has important implications for our understanding of the role of election pressures as constraints on sharing behavior in our highly polarized information ecosystem.