Asymmetric Polarization in Online Media Engagement in the United States Congress

In their online communications, political elites may choose to strategically eschew mainstream media sources and engage with alternative media outlets based on ideological and strategic considerations about the type of content they wish to legitimize or amplify to their followers. This is particularly true on social media which has become a fertile breeding ground for viral non-mainstream media content. Using an extensive dataset of social media posts sent from Members of the U.S. Congress between 2011 and 2022 (6.3 million tweets, 2.3 million Facebook posts), this article explores how media engagement in congressional online communications has evolved over time. The results suggest clear trends of asymmetric polarization, both in terms of media link sharing and media handle engagement, with Republican homophily and extremity of engagement growing steadily over time. This growing extremity is explained by changing Member behavior rather than changes in the composition of Congress and is primarily driven by more ideologically extreme Members of the Republican party increasingly engaging with rightwing and alt-right media. These trends have intensified in recent years, especially after the election of Donald Trump in 2016. Collectively, these results shed light on shifting ideological trends in media engagement and have important implications for our understanding of the relationship between political elites and the media in a highly polarized contemporary political environment.