The Dust Bowl was a series of dust storms (sometimes referred to as black blizzards) causing major ecological and agricultural damage to American and Canadian prairie lands from 1930 to 1936 (in some areas until 1940), caused by severe drought conditions coupled with decades of extensive farming without crop rotation or other techniques that prevented erosion. The fertile soil of the Great Plains was exposed through removal of grass during plowing. During the drought, soil dried out, became dust, and blew away eastwards and southwards, mostly in large black clouds. At times, the clouds blackened the sky all the way to Chicago, and much of the soil was completely deposited into the Atlantic Ocean.

This ecological catastrophe, which began as the economic effects of the Great Depression were intensifying, caused an exodus from Texas, Oklahoma, and the surrounding Great Plains, with over 500,000 Americans left homeless. Many Americans migrated west looking for work while many Canadians fled to urban areas like Toronto. Some two-thirds of farmers in "Palliser's Triangle", in the Canadian province of Saskatchewan, had to rely on government aid to survive. This was due mainly to drought, hailstorms, and erratic weather rather than to dust storms such as those which were occurring on the U.S. Great Plains farther south. Some residents of the Plains, in especially Kansas and Oklahoma, fell prey to illnesses and death from dust pneumonia and the effects of malnutrition.