The United States has more tornadoes than any other nation, and the majority of these twisters occur throughout the central states, an area known as Tornado Alley. About 200 tornadoes occur in Tornado Alley every year. The area is centered on northern Texas, Nebraska, Kansas, and Oklahoma (which has the highest percentage of severe tornadoes). Tornado activity, however, is also quite high in Louisiana, Mississippi, Alabama, Missouri, Arkansas, Kentucky, Tennessee, Illinois, Indiana, Iowa, and Ohio. The reason why there are so many tornadoes in Tornado Alley is that warm, moist air from the Gulf of Mexico moves northward and hits the dry air coming from the West as well as uplifting air currents. These are the perfect conditions, evidently, for tornado formation.