I am curious how they could tell. With so many people coming and then leaving in the subsequent outbreaks could be anywhere, even along the route of travel. Sturgis itself has 6k people (IIRC) so if they got hit you could see it but if my dog's vet from RI goes out there,, gets it, stops in Indiana on the way home, gives it to hotel worker, and then spreads it to friends in RI- who announces the contact tracing to show it had an effect.