May 21, 2020 – Social distancing is the core policy response to COVID-19. But as federal, state, and local governments begin opening businesses and relaxing shelter-in-place orders worldwide there is a lack of quantitative evidence on how policies in one region affect mobility and social distancing in other regions. In particular, no one has measured the consequences of uncoordinated regional policies adopted in the presence of such spillovers.

We know that pandemics are interdependent phenomena. Viruses, and people’s adherence to the government policies designed to contain them, spill over from region to region. It is less well known, however, how behavioral responses to the pandemic and to government mitigation policies spread as a result of social influence.

The Social Analytics Lab at the MIT Initiative on the Digital Economy (IDE) just released a comprehensive study of the cost of uncoordinated responses to COVID-19. We combined daily, county-level data on shelter-in-place and business closure policies with movement data from more than 27 million mobile devices, social network connections among over 220 million Facebook users, daily temperature and precipitation data from 62,000 weather stations, and county-level census data on population demographics to estimate the geographic and social network spillovers created by regional policies across the United States. We then used our empirical estimates to calibrate a model of what we call the “loss from anarchy” created by states failing to coordinate responses to these spillovers.

We found that peoples’ behaviors are influenced not just by those in their local communities; social connectivity is often as important as geographic proximity. Social networking through mobile phones, video conferencing, and social media can substantially alter perceptions of the effectiveness of local policies. Therefore, it is likely that individuals’ mobility and adherence to social distancing are impacted by the policies of neighboring and distant regions where their social network connections reside, not only by local mandates. Put differently, a local government’s social distancing policy may significantly impact the health outcomes of other communities, near and far.