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.
Tornado Alley
No state is entirely free of tornadoes; however, they occur more frequently in the Central United States, between the Rocky Mountains and Appalachian Mountains. Texas reports the most tornadoes of any state due to its large size, in addition to its proximity to Tornado Alley. Kansas and Oklahoma ranked first and second respectively in the number of tornadoes per area, per data collected through 2007, however in 2013 statistics from the National Climatic Data Center show Florida ranked first. Although Florida reports a high number and density of tornado occurrences, tornadoes there rarely reach the strength of those that sometimes occur in the southern plains. Regionally, the frequency of tornadoes in the United States is closely tied with the progression of the warm season when warm and cold air masses often clash.