What is the importance of the setting in Of Mice and Men?

The different settings serve as the backdrop to amplify the characterizations in Of Mice and Men.

The setting of the the Salinas River bank that opens and closes the novella is extremely important.  This is where we learn of the dreams that George and Lennie share.  It is also where we understand the power of hope that drives both men.  In the second and third chapters, the setting of the bunkhouse is where we learn more of the lives of the migrant workers who toil on the ranch. This setting helps us gain more insight into the people who move from place to place in order to find work in the 1930s.  We learn about how Candy lost his arm and the pain he experiences in losing his dog, as well as small characters's lives like Bill Tenner who used to work a cultivator and then moved on from the ranch. 

The setting is also important when the action shifts to Crooks's quarters.  The pain of segregation is explored when Lennie enters Crooks's room.  At this instant, the setting shows how racial discrimination enhanced the economic hardship of the 1930s.  Finally, the setting of the barn is essential to Of Mice and Men.  It is here where Curley's wife dies, and where George and Lennie eventually learn that their dreams for the future lie in ruins.  In these examples, Steinbeck uses different settings to amplify the characters' experiences.