What human rights issues were in the book of mice and men?

The book of Mice and Men had talked about the racial discrimination that was happening in the United States.  The author had written down that there was an evident inequality among the inhabitants in the United States. He had differentiate how the people were treated during his time,

1. seasonal

2. frictional unenployment

3. the number of the labor force multiplied by 100 and then subtract the number of unemployed.

4. 4%

5. an increase in prices