Why did Herbert Hoover become so unpopular?

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Why did Herbert Hoover become so unpopular?
Was this fair?
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Who was Herbert Hoover?

• 31st President of the United States (March 1929
  to March 1933)
• Major careers engineering, international relief,
  government and politics
• Republican
• Defeated by FDR in 1933 elections
• President during the Great Depression

1874-1964
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Hoover