On August 21, 1883, a devastating tornado affected southeastern portions—the Driftless Area—of the U.S. state of Minnesota. The massive tornado, retrospectively estimated to have been an F5 on the modern Fujita scale, caused at least 37 deaths and over 200 injuries. The tornado was part of a tornado family, a series of tornadoes produced by a supercell, that included at least two significant tornadoes across Southeast Minnesota on August 21. A third significant tornado occurred two hours before the main event hit Rochester. The Rochester tornado indirectly led to the formation of Saint Mary's Hospital, now part of the Mayo Clinic. The tornado closely followed destructive tornadoes a month earlier in the same area: on July 21, two significant, deadly tornadoes hit the area, including an F4 tornado family that killed four people in Dodge and Olmsted Counties, especially near Dodge Center.