Are COVID fatalities in the US higher than in the EU, and if so, why?

The COVID crisis has severely hit both the United States and Europe. We construct comparable measures of the death toll of the COVID crisis suffered by US states and 35 European countries: cumulative fatalities attributed to COVID at 100 days since the pandemic's onset in a particular nation/state. When taking account of demographic, economic, and political factors (but not health-policy related factors) we find that, controlling for population size, cumulative deaths are between 100 and 130% higher in a US state than in a European country. We no longer find a US/EUROPE gap in fatalities from COVID after taking account of how each nation/state implemented social distance measures. This suggests that various types of social distance measures such as school closings and lockdowns, and how soon they were implemented, help explain the US/EUROPE gap in cumulative deaths measured 100 days after the pandemic's onset in a state or country.