Tornado Alley is a colloquial term for the area of the United States where tornadoes are most frequent. The term was first used in 1952 as the title of a research project to study severe weather in parts of Texas, Oklahoma and Kansas only.

Although the boundaries of Tornado Alley are not clearly defined, its core is northern Texas, Oklahoma, Kansas, and Nebraska. Some research has indicated that tornadoes are becoming more frequent in the northern parts of Tornado Alley where it reaches the Canadian prairies.