Is the alternation consistent, or are there deviations?
How does this focus on the migrants
I think you are missing part of this. What was the "latter"?
Oh, I'm sorry, I am missing the beginning. It's this:
Steinbeck's narration alternates between the specific story of the Joad family and the larger story of all the Dust Bowl migrants.
Hey, when you ask a question put the short part or main question in the first part and the longer stuff (not too long) in the additional info. part or the question won't post right. I think I get it though. Simply Steinbeck needed to link the Joad's plight to he historical narrative of the time.
