A farmer and his sons walk through a dust storm in Cimarron County, Oklahoma, United States, during the Dust Bowl period. Between 1930 and 1940, severe drought coupled with decades of extensive farming without crop rotation, fallow fields, cover crops or other techniques to prevent erosion, led to major ecological and agricultural damage to American and Canadian prairie lands. Millions of acres of farmland became useless, and hundreds of thousands of people were forced to leave their homes.Photo: Arthur Rothstein; Restoration: Michel Vuijlsteke