Michigan experienced two large spikes of new cases at 10 and 15 days respectively following the armed April 14 protest in Lansing. There was debate at the time as to the sources, but if it isn't a causal relationship, it's at least one hell of a coincidence.
I think this is telling on how much of a difference masks make.
Experts say the outdoor demonstrations were in the sun and wind. In addition, people were in motion and most were wearing masks.