SIOUX FALLS, S.D. (AP) — The hundreds of thousands of bikers who attended the Sturgis Motorcycle Rally have departed western South Dakota.

But public health departments in multiple states are trying to measure how much and how quickly the coronavirus spread in the bars, tattoo shops and gatherings before people traveled home to nearly every state in the country.

The city of Sturgis is conducting mass testing for its roughly 7,000 residents.

But health departments in at least six states are also trying to track outbreaks from the 10-day rally which ended on Aug. 16.

They face the task of tracking an invisible virus that spread among rallygoers who then traveled to over half of the counties in the United States.

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