1,200–2,500 Peshtigo Fire, Wisconsin United States October 8, 1871
The single worst wild fire in U.S. history, in both size and fatalities, is known as the Great Peshtigo Fire which burned 3.8 million acres (5,938 square miles) and killed at least 1,500 in northern Wisconsin and the Upper Peninsula of Michigan during the week of October 8-14, 1871. Many sources put the size of the fire at 1.2-1.5 million acres but that included only the area that was completely burned and not the additional 2.3 million acres in surrounding counties that also suffered burn damage. Unattended fires at logging camps in the area most likely caused the fire. After a long hot and very dry summer strong warm autumn winds from the southwest fanned the fires out of control. Fire tornadoes were reported at several locations and the fire became so hot that people taking refuge in rivers were boiled to death.