Carol is the novel's central figure, the person through whose eyes we view Gopher Prairie and its inhabitants. College educated and culturally sophisticated, Carol pursues a career after graduation and dreams of turning a prairie village into a sophisticated, beautiful place. An orphan from the age of thirteen, Carol often grieves the loss of her father and constantly yearns for his understanding, love, and protection. When Carol marries Dr. Will Kennicott and moves to Gopher Prairie, she dreams of rebuilding the ugly, small town. However, as an incurable romantic, she does not achieve any realistic results because the town steadfastly resists change. Carol also lacks the steadfast spirit of a doer, remaining instead a thinker and a dreamer. She therefore achieves little in the way of her goals, rebelling inwardly more than outwardly. We may sympathize with Carol's restless plight to achieve individual happiness and social reform (as Lewis himself did), but may also see her as immature and inordinately romantic. Carol feels easily discouraged and self- conscious of the townspeople's criticism, lacking the backbone needed to be a true rebel.
As an independent and intelligent woman whose life does not revolve around domestic duties, Carol reflects the changing roles of women at the turn of the century. Women were at last granted the right to vote in 1920, the year Main Street was first published. Carol's desire to change Gopher Prairie and the town's resistance to change are the primary conflicting forces within the novel. At the end of the novel, Carol vows to continue fighting and not be satisfied with the traditional woman's role: "I do not admit that Main Street is as beautiful as it should be! I do not admit that dishwashing is enough to satisfy all women! I may not have fought the good fight, but I have kept the faith." Carol's support of the women's movement, socialism, and the labor movement further reflects the progressive spirit of early twentieth-century America, a time when many people supported social activism. Carol, in this sense, represents the spirit of change. Furthermore, she represents the author himself in many ways, as Lewis admitted that he based the character of Carol largely on himself.
Lewis uses Carol's negative perception of small-town America to satirically attack contemporary American society. Such an attack on small town America created a controversy in Lewis's time, as such criticism was revolutionary to a public that was more accustomed to nostalgia for traditional small-town life. Lewis brilliantly conveys Carol's distaste for Gopher Prairie from her first day in town, strolling down Main Street. She finds the townspeople unsophisticated, materialistic, conservative, narrow-minded, and self-righteous. They, on the other hand, consider their town the greatest place under the sun and resent an outsider's criticism. Trapped by tradition and by the complacency of the townspeople, Carol moves from one idea of reform to another. Unable to achieve any of her desired reforms, she seeks to mentally escape Gopher Prairie through books, nature, and a romantic friendship with a young man named Erik. Carol's character develops significantly as the novel progresses. When she leaves Gopher Prairie and moves to Washington, she gains maturity and a greater understanding of her place in the world. She more or less comes to terms with the fact that she belongs in Gopher Prairie, so she returns.
The novel's secondary protagonist, the practical and content Kennicott provides a foil to his imaginative and restless wife. While Carol longs to bring beauty and culture to Gopher Prairie and create social reforms, Will remains comfortable with his hometown as it is. While she is romantic and interested in the fine arts, he is realistic and materialistic. Although he is intelligent and insightful, he does not appreciate poetry or drama as his wife does, preferring cowboy movies to the theater. Throughout the novel, Dr. Kennicott fails to understand his wife's dissatisfaction with the town, instead absorbing himself in his profession and in small practical duties such as fixing his furnace or investing in land. The literary critic H.L. Mencken wrote, "To Will Kennicott as to most other normal American males, life remains simple—do your work, care for your family, buy your Liberty Bonds, root for your home team, help to build up your lodge, venerate your flag." While Carol finds the people of Gopher Prairie unimaginative and unsophisticated, Will considers them kind and friendly. He himself is dull but also friendly and easygoing. In all, he remains a stable, reliable, and unexciting character throughout the novel. While Carol's character matures by the end of the novel, Kennicott's character remains the same.
Although Will is rather dull compared to his wife, he is also a heroic doctor who can handle emergencies with calm and competence. In Chapter 15, Lewis describes Kennicott's profession in detail and, like Carol, expresses admiration for his professionalism and dignity. Lewis himself admitted that Kennicott's prototype was his father, Dr. E.J. Lewis. Some critics have remarked that Lewis' conflicting portraits of Kennicott—one presenting Kennicott as a dull, unimaginative boor and the other presenting him as a hero—reflect the author's own mixed feelings of antipathy and admiration toward his strict physician father. However, Lewis maintained that he intended the portrait to be complimentary.
The Kennicott's marriage proves to be a major theme in the novel. Lewis presents their marriage realistically rather than idealistically, reflecting the modern stresses of marriage. As Kennicott continually fails to understand his wife's dissatisfaction with Gopher Prairie, their marriage continues to deteriorate. However, Will never ceases to believe that his wife will come to love and accept the town as it is. He has an unswerving affection for Carol, tolerating her ideas and activities— such as her friendships with the Bjornstams and with Erik—while gently condemning them at the same time.
In many ways, the conservative Kennicott represents Gopher Prairie itself. He resists change and shares Gopher Prairie's practical and materialistic personality. The final scene of Main Street, in which Will and Carol talk, encapsulates much of the nature of their contrasting personalities. While the dreamy Carol imagines future social reforms she might engender, the practical Kennicott thinks only about the weather and his storm windows.