Steinbeck uses setting in 3 different ways:
1. He portrays the society and culture of the time. Not many people can relate to life on a ranch anymore, nor can they relate to times when people had very little. The description of the bunkhouse in chapters 2 and 3 demonstrates how few items people actually had. The mattresses were of straw, and the men had an apple box nailed to the wall to function as their locker or shelves. The men all shared a room. Little light got into the room even during the day.
2. He uses significant locations as symbols. The pool by the river is the place where the story begins and ends. It helps establish the Dream of the boys as it is serene like their own little ranch would be. It is calm and peaceful just like Lennie's death. This pool seems to symbolize hope and peace.
3. He lets setting compliment character. If you take a look at Crooks' room in chapter 4, you can see the books and supplies described express that Crooks doesn't have many friends, nor is he mobile like so many of the other guys.
How he presents setting:
Steinbeck uses the beginning of every chapter to paint the image of a room or location in which that chapter's activity is going to take place. He often uses vivid images by describing sensory details. Furthermore, he picks items to describe that could have some symbolism. For example, in the bunkhouse he describes streaks of light coming through the slats of the walls to demonstrate the darkness in that room. Quite often light and dark have additional meanings. In the beginning scene, the water seems important as so many animals interact with it. Water often represents life. It could be argued that in the end, life is finally offered to Lennie in his death as many believe in a perfect afterlife. This takes place in the same location at that pool of water.