Why did John Steinbeck write "The Grapes of Wrath"?

John Steinbeck wrote "The Grapes of Wrath" to tell the tale of the poor working and living condition of California's migrant workers in the 1930s. The book came out in 1939.

"The Grapes of Wrath" was an immediate success for John Steinbeck. It was a bestselling novel that won a Pulitzer Prize and a National Booksellers Award. The novel earned Steinbeck a great deal of notoriety and turned him into a celebrity.

After the success of this book, Steinbeck went on to tell tales of World War II and of the suffering he saw in the soldiers. He went on to win a Nobel Prize for literature in 1961.