The Great Chicago Fire occurred on October 8-10, 1871. The fire killed 250 to 300 people, left 100,000 homeless - about one third of the population, burned 2,000 acres, and destroyed 17,500 buildings. Most buildings, sidewalks and roads were made of wood. Summer and early fall were hot and dry. A cold front moved through the Midwest on Sunday October 8 producing strong southwest winds, which helped fan the flames and spread the fire.
Diorama of the Chicago Fire from the Chicago History Museum
The dry conditions and strong southwest winds that led to the Chicago fire also whipped up other fires in Wisonsin and Michigan, including the great Peshtigo Fire. The Peshtigo fire was the deadliest fire in U.S. history. It is estimated that 1200 to 1500 people were killed and 1.2 million acres were burned. Hardest hit was the town of Peshtigo, where 800 people lost their lives. Eyewitness accounts described a wall of fire a mile high, five miles wide and moving at 90 mph. The intense flames generated a fire tornado that threw rail cars and houses into the air. http://www.crh.noaa.gov/grb/