Description from website below:
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Published in 1939, John Steinbeck's novel The Grapes of Wrath drew attention to the hardshipsfaced by the "Okies": poor farmers who moved from the Dust Bowl area to California in search of work. While writing the book, John Steinbeck visited Bakersfield, California and based his book on Arvin Federal Government Camp which he portrayed as "Weedpatch Camp."

This camp exists today and is still used by migrant workers.
http://www.weedpatchcamp.com/