In the play "All My Sons" the significance of the setting contributes to the overall theme which is the pursuit of the American Dream. The setting for the play is Joe Keller's backyard. In the backyard of the family home which Joe Keller has worked hard all his life to acquire and keep, the judgement of his actions takes place. This is typical of post WW II, where people made lots of money from the war when all factories were converted to support the war effort.
Joe Keller stays in his backyard where he feels justified in what he did, providing for his family, keeping his business alive, making sure that he was able to pass it on to Chris his other son.
"The setting of All My Sons, the Keller's backyard in a small Midwestern town shortly after World War II has a significant role in the play. The setting suggests comfort and isolation from the community."
All the other characters and forces that drive the conflict of this play come to Joe Keller in his backyard. Little by little his comfortable protective environment is stripped away, either by character or by force of nature.
The opening of the play includes the fallen tree, that was knocked down in the previous night's storm, which was planted in memory of Larry, the Kellers' son who is missing in action for three years.
By keeping the action in the backyard, the author forces the reader, viewer to understand Joe Keller's world and his views, his home, his business, everything connected with achieving the American Dream, which he has done, are what drives his actions. His motives are expressed through the understanding of the simplicity of purpose that Joe Keller has in shipping faulty parts to the military which resulted in the deaths of 21 pilots.
But that is not all that Joe Keller has done to protect his home and his family and his achievements, he has lied. In order to save himself, on appeal, Joe Keller lies to get out of jail, thus leaving his former business partner, Steve Deever in jail fully responsibile for the decision of shipping the cracked cylinder heads.
The home is so important to Joe Keller, along with everything that he worked so hard to protect, that when it falls apart, it becomes too much for him.