The Evolution of Polarization in Online Conversation: Twitter Users’ Opinions about the COVID-19 Pandemic Become More Politicized over Time

Political polarization on social media has been extensively studied. However, most research has examined polarization about topics that have preexisting associations with ideology, while few studies have tracked the onset of polarization about novel topics or the evolution of polarization over a prolonged period. The occurrence of COVID-19 provides a unique opportunity to study whether social media discourse about a novel event becomes increasingly polarized along ideological lines over time. This paper analyzes trends in Twitter polarization in relation to COVID-19 and other geopolitical events of 2020. The first two studies use topic analysis to examine the evolving difference over time in discussions of COVID-19 and other topics by liberals and conservatives on social media. COVID-19-related polarization is initially absent but gradually increases over time, in contrast to polarization related to other events. A third study examines structural polarization in retweet networks and finds that the frequency of counterpartisan retweets reduces over time. Across all three studies, we find evidence that Twitter discussion of COVID-19 has become more polarized over time.