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.
Canada Tornado Alley
Technically speaking, no province or territory is entirely free of tornadoes; however, they occur more frequently in the Central Canada and Southern Canada, between the Rocky Mountains and the Great Lakes and between the Great Lakes and the St. Lawrence River.