In the 1930s, several years of drought affected over 100 million acres in the Great Plains from North Dakota to Texas. For several decades before this drought, the invention of modern farming equipment such as gasoline tractors and harvester-combines had allowed farmers to plow more prairie than ever before, removing the grasses with deep root systems and planting shallow-rooted crops. When the soil became extremely dry from lack of rain, strong prairie winds easily removed huge amounts of soil from the farms, forming dust storms. This region was called the Dust Bowl.