Tornado Alley
Although the official boundaries of Tornado Alley are not clearly defined, its core extends from northern Texas, Oklahoma, Kansas, Nebraska, into South Dakota. States such as Missouri, Iowa, Minnesota, Wisconsin, Illinois, Indiana, and western Ohio are sometimes included in Tornado Alley. Some research suggests that tornadoes are becoming more frequent in the northern parts of Tornado Alley where it reaches the Canadian prairies.
Dixie Alley
Although tornadoes are less frequent in these states than they are in the southern Plains, the southeastern states have had more tornado-related deaths than any of the Plains states (excluding Texas). This is in part due to the relatively high number of strong/violent long tracked tornadoes and higher population density of this region, as well as the Southern United States having the highest percentage of manufactured homes in the US, where 63% of the overall tornado-related fatalities occur. According to the National Climatic Data Center, for the period January 1, 1950 – October 31, 2006, Alabama and Kansas received the largest amount of F5 tornadoes. Complicating matters is that tornadoes are rarely visible in this area, as they are more likely to be rain-wrapped, embedded in shafts of heavy rain, and that the hilly topography and heavily forested landscape makes them difficult to see.