The Dust Bowl was the result of a period of severe dust storms that greatly damaged the ecology and agriculture of the American and Canadian prairies during the 1930s. The phenomenon was caused by a combination of natural factors (severe drought) and man-made factors: a failure to apply dryland farming methods to prevent wind erosion, most notably the destruction of the natural topsoil by settlers in the region. The drought came in three waves: 1934, 1936, and 1939–1940, but some regions of the High Plains experienced drought conditions for as long as eight years.
The Dust Bowl has been the subject of many cultural works, including John Steinbeck's 1939 novel The Grapes of Wrath, the folk music of Woody Guthrie, and Dorothea Lange's photographs depicting the conditions of migrants, particularly Migrant Mother, taken in 1936.
With insufficient understanding of the ecology of the plains, farmers had conducted extensive deep plowing of the Great Plains' virgin topsoil during the previous decade; this displaced the native, deep-rooted grasses that normally trapped soil and moisture even during periods of drought and high winds. The rapid mechanization of farm equipment, especially small gasoline tractors, and widespread use of the combine harvester contributed to farmers' decisions to convert arid grassland (much of which received no more than of precipitation per year) to cultivated cropland. During the drought of the 1930s, the unanchored soil turned to dust, which prevailing winds blew away in huge clouds that sometimes blackened the sky. These choking billows of dust - named "black blizzards" or "black rollers" - traveled cross-country, reaching as far as the East Coast and striking such cities as New York City and Washington, D.C. On the plains, they often reduced visibility to or less. Associated Press reporter Robert E. Geiger happened to be in Boise City, Oklahoma, to witness the "Black Sunday" black blizzards of April 14, 1935; Edward Stanley, the Kansas City news editor of the Associated Press, coined the term "Dust Bowl" while rewriting Geiger's news story.