A massive storm sends millions of tons of topsoil flying from across the parched Great Plains region of the United States as far east as New York, Boston and Atlanta.
At the time the Great Plains were settled in the mid-1800s, the land was covered by prairie grass, which held moisture in the earth and kept most of the soil from blowing away even during dry spells. By the early 20th century, however, farmers had plowed under much of the grass to create fields. The U.S. entry into World War I in 1917 caused a great need for wheat, and farms began to push their fields to the limit, plowing under more and more grassland with the newly invented tractor. The plowing continued after the war, when the introduction of even more powerful gasoline tractors sped up the process. During the 1920s, wheat production increased by 300 percent, causing a glut in the market by 1931.