Tornado Alley
The term was first used in 1952 as the title of a research project to study severe weather in areas of Texas, Oklahoma, Kansas, South Dakota, Iowa, Missouri, Nebraska, Colorado, North Dakota, and Minnesota. It is largely a media-driven term although tornado climatologists distinguish peaks in activity in certain areas and storm chasers have long recognized the Great Plains tornado belt.
Michigan
The state averages 30 days of thunderstorm activity per year. These can be severe, especially in the southern part of the state. The state averages 17 tornadoes per year, which are more common in the state's extreme southern section. Portions of the southern border have been almost as vulnerable historically as states further west and in Tornado Alley. For this reason, many communities in the very southern portions of the state have tornado sirens to warn residents of approaching tornadoes. Farther north, in Central Michigan, Northern Michigan, and the Upper Peninsula, tornadoes are rare.