Tornadoes

Tornadoes occur more frequently within the continental United States, however, under the right conditions a tornado can occur anywhere in the world.  The Midwest is a haven for tornado formation because maritime tropical air from the south mingles with continental polar air from up north to form unstable conditions. These conditions can cause severe thunderstorms, hail, flash flooding and the occasional tornado. According to Wikipedia and http://www.weather.com/, there have been a reported 1407 tornadoes, but, only 1019 have been officially confirmed.  Of the 1019 confirmed tornadoes there were 36 casualities. Plus, there were 3 confirmed deaths in other regions of the world.  According to the Enhanced Fujita scale, which tracks the wind speed and damage a tornado creates, most of the tornadoes which touched down within the United States were either EF0 or EF1.  Recently, the United States had its largest outbreak of tornadoes within a 4 day period (occurred Oct 24-27, 2010); however none of the tornadoes went above a category EF2.
The largest casualty total for a tornado occured in the year of 1925. It was "widely accepted" that 695 people died within a tri state area.  The "tri-state tornado" happened in Missouri, Indiana, and Illinois.  Most of the people that perished were those that resided within southern Illinois. 

Tornadoes are one of nature's greatest phenomenoms but also a major threat to civilization.  A tornado can wreck havoc on a major city if the right conditions intensify to create an EF5.  Imagine the damage a 200 mph tornado can create, if we know how much damage a 125 mph hurricane can make.  I love states such as Texas and Louisiana, but, I moved away from those states because 1.) Texas is, I believe, the major hub for tornado formation and 2.) Louisiana gets its share of tornadoes too, but you also have to wonder about the chance of a hurricane coming ashore.  So, that's why I reside in little old Yuma, Arizona. Sure there's a chance a major earthquake may hit since we live along a fault line but I will take my chances.