The American Dream keeps Lennie and George going throughout the story because it provides hope in a world devoid of it.
One of the most important themes in the novella is the American Dream. George and Lennie, and later Candy, each embrace the idea that they can “make it.” Through hard work, saving up a “stake,” and focusing on a vision for the future, the spirit of the American Dream animates them. This dream is what sustains them in both good and bad times. It is seen throughout the story. As early as the first chapter, the American Dream drives both men. Before they go to sleep, Lennie asks George to tell him about "their place" and the dreams they share. The American Dream accompanies them when they wake up and when they go to sleep.
In the second chapter, Steinbeck presents how dreams and sacrifice go together. It is clear that George and Lennie deserve better than the job on the ranch, evident in the disrespect at the hands of Curley and his father. Even though Lennie tells George how uncomfortable he is being on the ranch, George insists that they are both tethered to it in order to “to make a stake” working on the ranch. Steinbeck reflects the struggle of life in the 1930s. George and Lennie are able to endure difficulties because of their hopes in the American Dream and a place they can call their own.
Even in the ending, when it is clear that reality has interfered with their aspirations, the American Dream keeps both men going. Lennie asks George to tell him the story about their dreams. When George kills Lennie, he does so with the vision of their dream as the last thing they both share. It is for this reason that some of George's last words to Lennie are "I gotta, we gotta," referencing how their dream is with the until the very end.
While George and Lennie do not accomplish their American Dream, Steinbeck does not repudiate the need for dreams. Rather, it seems that having dreams, even if they are not accomplished, is better than living in a world where they do not exist. Dreams keep people going, allowing individuals to endure difficulties. Steinbeck creates George and Lennie as more endearing than the traditional migrant worker who moves from job to job without an overall purpose in part because of the American Dream that sustains and define them.