By the mid-1930s, the drought had crippled countless farm families, and America had fallen into the Great Depression. Unable to pay their mortgages or invest in the kinds of industrial equipment now necessitated by commercial competition, many Dust Bowl farmers were forced to leave their land. Without any real employment prospects, thousands of families nonetheless traveled to California in hopes of finding new means of survival. But the farm country of California quickly became overcrowded with the migrant workers. Jobs and food were scarce, and the migrants faced prejudice and hostility from the Californians, who labeled them with the derisive epithet “Okie.” These workers and their families lived in cramped, impoverished camps called “Hoovervilles,” named after President Hoover, who was blamed for the problems that led to the Great Depression. Many of the residents of these camps starved to death, unable to find work.
When Steinbeck decided to write a novel about the plight of migrant farm workers, he took his task very seriously. To prepare, he lived with an Oklahoma farm family and made the journey with them to California. When The Grapes of Wrath appeared, it soared to the top of the bestseller lists, selling nearly half a million copies. Although many Oklahomans and Californians reviled the book, considering Steinbeck’s characters to be unflattering representations of their states’ people, the large majority of readers and scholars praised the novel highly. The story of the Joad family captured a turbulent moment in American history and, in the words of critic Robert DeMott, “entered both the American consciousness and conscience.”
-
http://www.sparknotes.com/lit/grapesofwrath/context.html