Colleges and universities that reopened with in-person classes are linked to a surge in coronaviruses cases in the local area, a new study has found. Researchers estimated that 3,200 cases nationwide occurred daily as a result. The study, which is still pending peer review, will be published Tuesday on the preprint server medRxiv. The researchers used cellphone GPS data to track people’s movements then calculated infection rates in the surrounding county from mid-July to mid-September. Comparing before and after students showed up, they correlated resuming in-person teaching with between 1,100 to 5,3000 excess cases per day. When colleges reopened with largely online-only class, they found smaller upticks in case counts compared to schools with in-person classes, particularly when students came from other hot-spot zones. The authors said they shared the findings in advance of normal peer review given the public health implications.