Kennicott feels hurt that Carol does not show any interest in the town's boosting campaign. He protests that he will no longer bear Carol's rebellion against the town. Carol tells him that she does not belong to Gopher Prairie and wants to leave. For a month, they argue about Carol's decision to leave, hurting each other a great deal in the process of discussion. In October, Carol and Hugh take a train to Washington, D.C. Although Carol tries to play make- believe games with Hugh on the train, she sadly reflects that her practical and unimaginative son resembles his father. The town newspaper later announces that Mrs. Kennicott has gone to Washington to help out the war activities.
Carol finds employment in the Bureau of War Risk Insurance. She finds the office dull but enjoys the city life, especially the cultural attractions and beautiful buildings. She mixes with people who keep up on politics and contemporary social issues, unlike the people in Gopher Prairie. In particular, she makes many acquaintances with women in the suffrage movement. However, Carol also talks to many women from small towns who are currently living in Washington. Through them, she realizes that Gopher Prairie actually looks good compared to other small towns. Gradually, Carol realizes that she has tried to wage war against individuals rather than against larger institutions like the church and the country—the institutions that are really to blame for making a town like Gopher Prairie what it is.
After a year, Carol feels tired of office work. She encounters Percy Bresnahan in Washington, and a friend in the army tells her that many people consider Bresnahan a good salesman but an idiot who harasses the government and aeronautics section. At the movies, Carol recognizes Erik Valborg onscreen playing a bit part adequately, and feels sorry for him.
Thirteen months after her departure, Kennicott visits Carol in Washington. She feels touched seeing her husband all dressed up. She takes him sightseeing and introduces him to all her friends. He gives her news of Gopher Prairie and shows her photographs of the town, just as he had showed her photographs when he first courted her. However, Kennicott does not ask her to return. He only indicates that he would welcome her home but wants her to come back only if she really wants to do so. Carol replies that she does want to return to Gopher Prairie but still wants to feel free to criticize it.
Carol and Kennicott take a trip around the South, which he refers to as a "second wooing." He tries to confess about his affair with Maud Dyer, but Carol tells him not to say anything. Kennicott returns to Gopher Prairie alone, and Carol decides to return in a couple of months. Carol no longer feels hatred to the town, only sympathy and understanding. She decides that she must accept people as they are but will still continue to question everything. When Carol returns, she is pregnant with her second child.
When Carol returns to Gopher Prairie, she finds herself at home with the familiar faces. She also feels happy to have been missed by many of the townspeople who warmly welcome her back. However, she also realizes that nothing in Gopher Prairie has changed, except for a few building projects and a new school. She becomes active in town activities. One day, local men in a barbershop discuss Carol's return and decide to accept her.
Carol gives birth to a daughter, hoping that the child will continue her fight to make a better place. She tries to organize a Community Day but meets with opposition. As Carol and Kennicott prepare for bed, she remarks that she may not have won the battle against Gopher Prairie but feels satisfied that she has continued fighting. As Kennicott half-listens to her, he wonders about the storm windows and the weather.
We may find the ending of Main Street disappointing, as the novel ends with an impasse in which nothing has really changed. Carol's long struggle with Gopher Prairie finally prompts her to leave, only to return again and settle down, again seemingly unsatisfied. As Carol explains to her husband that she has "fought the good fight," Kennicott replies, "Sure. You bet you have. Well, good night. Sort of feels to me like it might snow tomorrow." The fact that Kennicott—not Carol—has the last words of the novel may reflect the fact that Gopher Prairies has, in the end, defeated Carol. Kennicott remains a practical and unimaginative character to the last line, thinking about the weather and storm windows. Despite the seeming impasse, however, we may view the ending as happy. After all, the novel's two main conflicts—Carol's conflict with Gopher Prairie and her conflict with her husband—are resolved in the last chapter. Through Carol's "defeat," Lewis seems to admit that one person cannot reform a town, but he continues to support the need for reform.
Carol develops maturity when she lives in Washington, D.C. She discovers a world outside Gopher Prairie and realizes that she does not have to place so much importance on what the people of Gopher Prairie think about her. She also finds her work of filing correspondence letters to be monotonous and realizes that she is not really important to live in a big city. Furthermore, she finds the same dullness of Gopher Prairie in many of the people she meets in Washington. The problems of Gopher Prairie are the same problems everywhere, and the people of Gopher Prairie are the same types of people one can meet anywhere. Carol gains further insight when she realizes that Percy Bresnahan and Erik Valborg are not as great as she once imagined.
Most important, Carol develops an acceptance and even a fondness for Gopher Prairie. She does not really leave Gopher Prairie because the town remains in her consciousness; she constantly remembers the town and uses it as a reference point against which to compare Washington, D.C. In her conversations with other ladies who came from small hometowns, she even realizes that Gopher Prairie is actually a better place than other communities of its size.
We should remember that Lewis based Gopher Prairie on his hometown of Sauk Centre, a small town of a population of 3,000. Like Carol, Lewis felt a love- hate relationship to his hometown. Although Lewis fumes against the narrow- mindedness, mediocrity, and conformity of small-town life, he does not exempt large cities from criticism. Carol's office life proves dull and monotonous. Gopher Prairie, unlike Washington, provides her with a community network: she feels that there is friendship and warmth in Gopher Prairie while she feels anonymous in the big city. In Washington, Carol proves to have the "Village Virus," the virus mentioned by Guy Pollock in Chapter 13 to explain why ambitious people settle down in small towns and lose their ambition.
In Chapter 39, Carol's final homecoming contrasts to her first arrival in Gopher Prairie. At the end, she accepts the town and the people as they are. In the beginning, she feels nervous and shy, knowing no one, and only dreaming about completely reforming the town. Now, however, she feels anticipation seeing what she considers friendly, familiar faces again.
When Kennicott visits Carol in Washington, he shows her pictures of Gopher Prairie just like he had done when they first courted. When she sees the pictures for in Chapter 38, she sees "the porch of their own house where Hugh had played, Main Street where she knew every window and every face." In Chapter 2, she had seen only "streaky" pictures of "trees, shrubbery, a porch indistinct in leafy shadows, [and] lakes." The fact that the pictures in Chapter 2 are "streaky" and "indistinct" symbolizes Carol's detachment from the community. However, the pictures of her house and familiar faces in Chapter 38 symbolize her connection to the town with which she is familiar. In Gopher Prairie, unlike Washington, she can say to herself, "This is home."