Peshtigo, 1871
Credit: Getty Images

The Place: Wisconsin and Michigan
The Underlying Cause: Outdoor fires left to smolder
The Devastation: Approximately 3,780,000 acres burned and 1,500 lives lost in Wisconsin
What Is Noteworthy about This Fire: Extremely dry conditions and an unexpected change in weather likely fanned the flames of human-made embers into a firestorm. While dry weather and high winds are always high-risk conditions for fire, if there were no human-made fires left smoldering to begin with, this event may have been avoided entirely.