Cather's book is about immigration, romanticism, symbolism, classism, and sexism.
On one hand, the story is suppose to be about Antonia, the eldest daughter of recent immigrates to the American prairie. But it is more about what Antonia represents to those around her. Beauty, childhood, the prairie itself, a loose woman. Antonia, herself, might just represent the different views of America that everyone has, sometimes all at once.
Antonia's hardships and struggles represent different things to those around her, but she herself seems other, always other. In part because she is a new American, in part because she speaks her mind, and because she is a meek woman