  Are COVID-19 fatalities large when a federal government does not enforce
containment policies and instead allow states to implement their own policies?
We answer this question by developing a stochastic extension of a SIRD
epidemiological model for a country composed of multiple states. Our model
allows for interstate mobility. We consider three policies: mask mandates,
stay-at-home orders, and interstate travel bans. We fit our model to daily U.S.
state-level COVID-19 death counts and exploit our estimates to produce various
policy counterfactuals. While the restrictions imposed by some states inhibited
a significant number of virus deaths, we find that more than two-thirds of U.S.
COVID-19 deaths could have been prevented by late November 2020 had the federal
government enforced federal mandates as early as some of the earliest states
did. Our results quantify the benefits of early actions by a federal government
for the containment of a pandemic.
