6. Hurricane Ivan (2004) $23 billion
A big, long-lived hurricane, Ivan was the size of Texas. The storm spawned 119 tornadoes across states in the eastern U.S. In advance of the storm, about a thousand residents of New Orleans took refuge in the Superdome — a year before the infamous Hurricane Katrina. In Alabama, 270 zoo animals were evacuated. At the height of the outages, Alabama Power reported 489,000 subscribers lost electrical power — roughly half its subscriber base.