GEOGRAPHY AWARENESS WEEK! UNITED STATES

While the Great Plains states of Kansas, Nebraska, and the Dakotas, as well as parts of Texas, are collectively known as Tornado Alley for their frequent storms, the weekend was a reminder that Illinois, Indiana, Iowa, Michigan, Missouri, Ohio, and Wisconsin are also tornado-prone. (National Geographic News)

Use our resources to map tornadoes in the U.S.

Discussion Ideas

• Read through our activity “Tracking Violent Storms.” It suggests creating a choropleth map to represent tornadoes. A choropleth map is a map “in which areas are shaded or patterned in proportion to the measurement of the statistical variable being displayed.” The statistical variable here is the number of storms per state. Use our 1-Page Map of the United States and this information from the National Climatic Data Center (NCDC) to create a map.
  • Reviewing and eliminating some “Map Elements” from the 1-Page Map may help clarify the map. All of the “Other Features” (cities, rivers, points of interest) may not be relevant to this map.
  • Instead of a choropleth map, you may want to use the “Drawing Tools” and “Markers” to identify states most at-risk for tornadoes and violent wind storms. There’s even a tornado marker!

• “It turns out that the [phrase Tornado Alley] isn’t correct,” says the Weather Channel’s website, quoted in the Nat Geo News article. Does the map you made (with the NCDC’s data) support this? Take a look at “Tornado Alley” and “Dixie Alley” to see the traditional areas associated with tornadoes in the U.S.

• The Nat Geo News article, quoting The Weather Channel, says Florida endures more tornadoes per square mile than any other U.S. state. The NCDC’s map shows Texas receiving the most tornadoes, however. Is the Weather Channel or NCDC wrong?
  • Neither is wrong. The NCDC map shows the total number of tornadoes per state. The Weather Channel tracked the total number of tornadoes per state, per square mile. Texas endures more tornadoes, but it’s a big state with a lot of square miles. Florida has fewer total tornadoes, but they’re packed into a smaller space.
  • This map from the NCDC tracks tornadoes by state, for every 10,000 square miles. The Weather Channel’s assertion that Florida endures more tornadoes relative to its size is born out.