It is a challenge that public health officials have faced repeatedly as they try to understand how the coronavirus is making its way through the country: When people gather for a
large event and then return to states with different health departments, it is difficult to be sure whether the event was part of an outbreak.
The issue has stymied certainty about how the virus’s spread has been affected by events like a rally for President Trump in Oklahoma, protests in Minneapolis after the death of George Floyd, holiday weekend visits to the Lake of the Ozarks in Missouri, Mardi Gras celebrations in New Orleans and spring break trips to Florida.
The rally in Sturgis, one of the biggest regional events to proceed amid the pandemic, drew attention from all over. More than 350,000 vehicles had flocked into the small town during the first week of the event, according to the South Dakota Department of Transportation.
“It’s more than we anticipated by far,” said Dan Ainslie, the city manager of Sturgis.
Local officials had set up precautions — hand sanitizing stations and capacity limits inside some buildings. But many people went without masks, and some supporters suggested that a mostly-outdoor event did not require face coverings.
“You have to be careful, but at the same time, you have to live,” said Mike Petrocco, a Sturgis resident who has long offered his lawn as a campsite during rallies. Mr. Petrocco, 64, said that at one point this year he was hosting 16 people, and that he offered hand sanitizer, did laundry and cleaned every day.