In "An American Tragedy", what happens to Clyde's family after he moves to work with his uncle?
Keep in mind that Clyde didn't so much "move to work". He ran away from his home as a result of the car accident he was responsible for. He ran in shame, as he will continue to do throughout his life. He is lucky enough to run into his uncle, who is wealthy and owns a factory, and is kind enough to give Clyde a job.
Things are not so good back home. Esta meets a touring actor and becomes enamoured of him. She has a brief relationship with him that results in a pregnancy. He leaves, deserting her and avoiding his responsibility. Because the time period was severe upon both an unmarried woman and her offspring, Esta's mother and father adopt the child, trying to give him a chance in the world.
Clyde's parents move to Denver, where they try their best to raise Clyde's two youngest siblings. In Denver, they manage to set up a new mission. Seen in its best light, Clyde's parents establish their own church and homeless shelter in Denver. A less flattering view is that they remain impoverished and unsuccessful missionaries who struggle to get by in Denver, Colorado.