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Tornado Alley
The most tornado-prone region on Earth
Tornado Alley is the informal name for the swath of the central United States that sees more tornadoes than anywhere else on Earth. It has no official boundaries, but is usually centered on the southern Great Plains - Texas, Oklahoma, Kansas, and Nebraska - where the ingredients for violent thunderstorms come together with unusual frequency each spring and early summer.
The cause is geographic: warm, moist air streaming north off the Gulf of Mexico collides with cool, dry air spilling down from the Rockies, all under a fast high-altitude jet stream, spinning up the rotating supercell storms that breed tornadoes. In recent decades activity has seemed to drift eastward into a second zone sometimes called "Dixie Alley" across the Southeast. The marker here sits in central Oklahoma, near the heart of the classic alley and the national storm-prediction center in Norman.