Disasters!

Popular Mechanics has the 10 worst disasters of the century (in the USA). 1905-2005 I am guessing based on the dates they used which is odd considering it's 2007. Anyway, closest to home?:

1980: Mount St. Helens Eruption
One last earthquake turned the sleeping giant loose, and soon 230 sq. mi. of lush forest was entombed in a lunar wasteland. Fifty-seven fatalities and $1 billion of damage later, the eighth—and perhaps most famous—of our 10 Worst Disasters of the Century is now considered the dawn of American earthquake science—and a jumping off point for GPS.