America as a discovery
America is not just the setting of the novel; rather, America and American culture provide the broader context to a story whose real "setting" is really the marathon experience of adapting to a new home. As the mystery of what America really is unfolds itself before this family, a more true portrait of human culture is revealed, as well as the virtues and vices of American life which is famously spectral with plenty of extreme wealth and plenty of extreme poverty. They adapt gradually, but by the time they see what America really is, Maribel and her mother return to Mexico, convinced that they are more suited for life in that mode.
Mexico as a changing home
Mexico is visited in two sections of the book, the beginning and end. Although parts of the novel seem to be pointing semi-permanently or permanently away from Mexico, the plot eventually returns the family to their homelands. This means that Mexico is a symbol for time. The American experience interrupts two experiences of Mexico that are "before" and "after." The Mexico of "before" is symbolized by the dying father who once provided for the family. The new Mexico is unknown and will somehow respond to the radical cultural influences of America, as the family's experience suggests.
The innocent sufferer
The portrait of Maribel's life is pity-inducing and tragic, but this turns out to be a clever use of imagery. She is not necessarily dynamic in the character sense, but rather, she is dynamic in her abilities and her health. She is like a thermometer that provides the reader an accurate reflection of the cultural influences around her. She is also innocent from life's responsibilities, so her suffering is naturally symbolic. This points to the "Why do bad things happen to good people?" conundrum so famously explored by human literature.
Evil and empathy
Among that already-disappointing reality into which this family enters, there is another element of imagery that is astonishing. Instead of finding the promised land of America overflowing with milk and honey, this family finds a land whose milk and honey is fiercely protected by giants. What are the giants? Widespread apathy toward the suffering of others. That is an obvious shift from Mexican life (which is more community-oriented) to American life (which is less communal and more individual). Against this backdrop of social betrayal and bullying, we see a small symbolic love story between Mayor and Maribel which inspires hope. Empathy might be rare, but it is apparently very powerful, says the plot.
