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.
Tornadoes in the United States
In the Southwestern United States, New Mexico reported 485 tornadoes during the 1950 to 2006 period (NCDC figures), California reported 355, Arizona reported 209, and Nevada reported 75. New Mexico borders the notoriously tornado prone states of Texas and Oklahoma, hence the noticeably higher figures. Most of the tornadoes here happen in the very eastern part of the state. New Mexico's region and the desert landscape of the state help prevent the amount of twisters that happen in Oklahoma and Texas. Arizona and New Mexico experience regular summer thunderstorms during their monsoon season. These are sometimes tornadic but rarely produce violent tornadoes.