Published in 1939, by John Steinbeck. (wiki) Audiobook online at:
The movie version, done in 1940 and starring Henry Fonda, differs substantially from the novel, but focuses on the same, core elements: family, work, inequality, human squalor, inequality, injustice and greed.
See also this 3-minute video composing movie clips with the singing of ‘Brother, Can You Spare a Dime’, by Judy Colllins.
And, the original movie trailer (a classic example of 1940’s over-promotion):