The event attracted 365,979 and was the biggest mass gathering in the world since the pandemic was declared,
Organisers had predicted attendance would be about 250,000, down from an annual average of almost half a million.
The event went ahead despite 63% of the town’s 7000 citizens voting not to hold the rally after a gift wholesaler in nearby Rapid City threatened to sue the council.
Now, researchers from the University of Colorado Denver, Bentley University, University of California San Diego, and San Diego State University have used phone data to track the movements of Sturgis rallygoers and a complex (and maybe dubious) mathematic equation to estimate infection spread:
“In counties with the largest relative inflow to the event, the per 1000 case rate increased by 10.7% after 24 days following the onset of Sturgis Pre-Rally Events,” their report says.
“Multiplying the percent case increases for the high, moderate-high and moderate inflow counties by each county’s respective pre-rally cumulative COVID-19 cases and aggregating, yields a total of 263,708 additional cases in these locations due to the Sturgis Motorcycle Rally.
“Adding the number of new cases due to the Rally in South Dakota estimated by synthetic control (3.6 per 1,000 population, scaled by the South Dakota population of approximately 858,000) brings the total number of cases to 266,796 or 19% of 1.4 million new cases of COVID-19 in the United States between August 2nd 2020 and September 2nd 2020.”