We study the impact of college reopening in fall 2020 on county-level COVID-19 cases and deaths using the information of 1,076 randomly chosen four- and two-year undergraduate degree-granting colleges from the National Center for Education Statistics. These institutions include public, private nonprofit, and for-profit schools from fifty U.S. states and the District of Columbia. We match college and county characteristics using several methods and calculate the average treatment effects of three teaching modalities: in-person, online, and hybrid on COVID-19 outcomes up to 2 months after college reopening. In pairwise comparison, colleges reopened with in-person teaching mode were found to have about 35 percentage points more cases within 15 days of reopening, compared to those that reopened online, and the gap widens over time at a decreasing rate. Death rates follow the pattern with a time lag. However, colleges with hybrid mode reach up to the rates of inperson mode after some time. We also find that greater endowment and student population, bigger class size, and fewer Republican voters in the county are major predictors of choosing remote teaching modes over in person.

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