When we first meet Carol, her last name is Milford, and she's working her way through a quaint Minnesotan school called Blodgett College. From what we can tell, Carol is a smart and pretty young woman with her whole life ahead of her: "In her class there were two or three prettier girls but none more eager […] Every cell in her body was alive—thin wrists, quince-blossom skin, ingénue eyes, black hair" (1.2.2).
The phrase, "Every cell in her body was alive" does a great job of telling just how excited Carol is to explore her talents and to make a real difference in the world. This is young Carol in a nutshell.
During her time at Blodgett, Carol spends much of her time trying to figure which way she can make the biggest change in the world once she's out of school. After trying a few different things out, she decides that city planning is right for her. She likes the idea of moving to a small American town and using her knowledge of culture and art to transform it into a hip modern place. As she thinks to herself, "That's what I'll do after college! I'll get my hands on one of these prairie towns and make it beautiful. Be an inspiration" (1.1.25).
Unfortunately, Carol doesn't realize yet that the world is full of different kinds of people who might not be willing to change just because she wants them to.
Carol finally gets her chance to make a difference in the world after she marries Dr. Will Kennicott—or at least this is what she thinks will happen. She thinks that she's going to move to Will's hometown of Gopher Prairie and turn it into something beautiful. But as soon as she moves there, she realizes that the town is filled with a bunch of dull people and that she no longer has the opportunity to be a professional: "She could not have outside employment. To the village doctor's wife it was taboo" (7.2.3).
At this point, Carol realizes she is stuck in a new life as a doctor's wife in a boring town. So what's going to happen now to this young and idealistic girl from Blodgett College?
The thing that bothers Carol most about Gopher Prairie isn't necessarily its dullness; it's the way that everyone has their nose in everyone else's business. It seems like the people in town discuss everything about everyone, right down to tiny details about their clothing. This makes Carol feel claustrophobic and exposed, as we read at one point, "In her innocence she had not known that the whole town could discuss even her garments, her body. She felt that she was being dragged naked down Main Street" (9.2.32).
After a few years, the thing Carol fears most of all is the possibility that Gopher Prairie has ground her down into a dull person. She has these fears confirmed whenever she visits the large city of St. Paul, where she feels that people "thought she was a hayseed, she worried" (7.3.14). The Term "hayseed" in this case is like the term "hick," meaning that Carol fears that she no longer fits in with hip city folk the way she once did. All she wants to do is rage against the dullness of Gopher Prairie, but it's almost impossible for her to win against the three thousand other folks in the town who like their lives just fine.
It's fairly clear that Carol will never single-handedly transform a town of 3,000 people who don't want to change. Nevertheless, Carol decides she will never give in to the town's bland conformity; in fact, she flees in the opposite direction, embracing her individualism in a way that would strike many people as self-centered. As she thinks at one point, "When I die the world will be annihilated, as far as I'm concerned. I am I! I'm not content to leave the sea and the ivory towers to others. I want them for me! Damn Vida! Damn all of them!" (22.8.8).
By the end of the book, Carol has had a chance to move away from Gopher Prairie and live in Washington, D.C. for two years as a professional woman. She has enjoyed her time there, but she has also realized that even the big city will never be able to satisfy her desires. She finally moves back to Gopher Prairie, but she's determined not to think of this as an act of surrender. As she says to herself in the final scene, "I do not admit that Gopher Prairie is greater or more generous than Europe! I do not admit that dish-washing is enough to satisfy all women! I may not have fought the fight, but I have kept the faith" (39.8.10).
Carol will continue to find some comfort in the fact that she'll never be like the other people in town. She feels like her dissatisfaction with everything around her will keep her unique, and in some small way, that thought gives her comfort.
It's not totally clear whether Carol's problem stems from the fact that she's a woman in world with few options for women (other than homemaking and popping out some kids) or from the fact that she's a complex person searching for meaning in life, and meaning in life is a notoriously difficult thing to find. It's probably a combination of the two, which is one reason why at a certain point, Carol places all of her hopes on her daughter's future. Maybe then, Carol thinks, happiness will be possible.