The Sturgis Motorcycle Rally held in South Dakota last month may have caused 250,000 new coronavirus cases, according to an economic study focused on the public health costs of “superspreading” events. The 10-day rally attracted more than 400,000 people. Prolonged interactions between individuals at high frequencies, along with "minimal mask-wearing and social distancing by attendees," raised concerns that Sturgis would lead to increased transmission of coronavirus, according to a new study from the IZA Institute of Labor Economics.