This wide-open space is symbolic of the half-broke horses that are Lily and Rosemary. Lily cannot be contained in small spaces and this is evident when she and Jim try to survive in Phoenix. The ranch is a space somewhere between complete wilderness and the restrictive society they encounter in the city, making it the place where Lily and her daughter truly feel at home. 

In a one-room school, the teacher has complete control, while in a traditional public school, a teacher has to follow the rules established by the administration and the school board. Lily is best suited to teaching in small schools where she can the class in her own way, without being constantly monitored and this is exactly what happened when she was doing what she loved. This preference for smaller schools suggests her desire to have control over her own life. 

While this theme was never discussed openly in the book, there are signs of it throughout the entire novel. Lily is the personification of the feminist movement as she constantly asserts her independence and desire to be a true partner to her husband. She is the complete opposite of her weak mother, who suffers from the vapors and seems to thrive on being frail.