Carol Milford attends Blodgett College in Minneapolis in the early 1900s. One day, she escapes from class to look at the city skyline. Beautiful and vivacious, she has several male admirers, including a classmate named Stewart Snyder. During her senior year, Carol feels uncertain about choosing a particular profession. She definitely wants to make a career for herself, however, as she does not want to become a housewife. She possesses an interest in the arts and sociology and imagines becoming a social reformer for the poor. After reading a book on village improvement, she decides she would like to adopt some prairie town and make it beautiful.
As an orphan, Carol is on her own in the world. Her mother died when she was nine, and her kind, learned, and fun-loving died when she was thirteen. Her father, who had worked as a judge in Minnesota, had given her an unorthodox education, allowing her to read whatever she pleased.
Following the advice of her English professor, Carol takes a course in library studies in Chicago. During her graduation ceremonies at Blodgett College, Stewart proposes to her. She rejects his proposal, telling him that she wants to accomplish greater things than raising children and washing dishes.
In Chicago, Carol falls in with the art crowd, attending art museums, symphonies, and Bohemian parties. She feels shy and awkward, however, in the Bohemian circle. She returns to St. Paul to work as a librarian for three years. She reads enormously but does not find her life fulfilling. However, she continues to reject her male suitors until she finally meets Dr. Will Kennicott.
Carol meets Will Kennicott at a friend's house. He is a well-to-do physician in his late thirties from the small town of Gopher Prairie, Minnesota. The two get on remarkably well as Will proudly talks about his hometown and profession. Although he went to medical school in Minneapolis, he returned to practice in Gopher Prairie, as his heart has remained there. He suggests that someone like Carol could really enlighten a town like Gopher Prairie.
Kennicott courts Carol. Although she dislikes his materialism, she admires his honesty and finds him attractive. The two take long walks together around St. Paul. One day, they walk through the old section of the city built by fur traders. Will proposes to Carol. He shows her photographs of his hometown, which touch a cord in her heart, and she agrees to marry him and move to Gopher Prairie. She dreams about transforming the small town into a perfect village.
After a year of courting, Kennicott and Carol marry. They go on a honeymoon in Colorado, and then travel by train to Gopher Prairie. Observing the other passengers—poor farmers, tired-looking wives, and numerous children—Carol feels distressed that these people humbly accept their poverty and ignorance. She imagines how she could transform these people's lives for the better. Surprised by Carol's perception, Kennicott tells her that the farmers do not mind their hardship and are better off than she thinks. Many even possess telephones and Ford automobiles.
As the train stops in Schoenstrom—a town of 150 inhabitants that looks like a mining camp—Carol comments about the ugliness of the town to Will. However, he does not find the town ugly as she does, and he points out that Gopher Prairie is larger and more beautiful. He also points out a rich farmer he recognizes who lives in the town. Carol replies that people should use their wealth to beautify their town, but Kennicott does not understand her point of view. She looks out at the prairie, imagines the pioneers who came to build an empire, and wonders about the land's future.
Seeing Gopher Prairie for the first time from the train, Carol feels disappointed because the town looks just like all the other ugly prairie towns she had passed on the train. However, noticing Kennicott's excitement, she conceals her disappointment. Kennicott's friends Sam Clark, Dave Dyer, Jack Elder, and Harry and Juanita Haydock welcome the couple home at the train station. Carol feels shy but touched by their warm reception. Sam drives the Kennicotts home. Kennicott's old-fashioned house disappoints Carol, but she again conceals her disappointment as her husband eagerly shows her around the house.
Lewis begins the novel with a vivid portrait of Carol: "On a hill by the Mississippi where Chippewas camped two generations ago, a girl stood in relief against the cornflower blue of the Northern sky." As the English novelist E.M. Forster noted, Lewis largely functions as a photographic writer by creating carefully detailed images that seem as real as snapshots. Lewis paints another remarkable picture of the train's passengers as he describes the characters' appearance and mannerisms.
Lewis's strength as a writer lies in his ability to set a particular scene more than to tell the story. Throughout the novel, he carefully recreates town life down to its smallest detail. The setting of Gopher Prairie, stemming from Lewis's focus on recreating a particular place at a particular time, often overshadows the plot and main characters. In fact, many have criticized the novel for lacking a coherently sketched plot. Instead, the plot combines a series of episodes—Lewis's snapshots—into what amounts to a photographic album. After all, the novel contains many chapters that are further divided into several sub-sections.
Throughout the novel, Lewis references the influence of the past on the present. As Carol realizes later, many Midwesterners retain the conservatism and pioneer spirit of their ancestors. Carol, on the other hand, strikes us as a remarkably modern woman for her time. She chooses a profession rather than marriage, takes an interest in intellectual subjects (books, music, and art) and holds liberal opinions about contemporary social issues (labor unions and women's rights, among others). In the first paragraph of the novel, Carol thinks only about the present (her classes) rather than the past (the Chippewas and the Yankee fur traders).
The first chapter provides an insight into Carol's personality and her family background. The fact that she holds many unconventional opinions may be explained by the fact that she has had an unconventional upbringing. Carol strikes us as a dreamer, and she may even strike us as somewhat silly. After all, she imagines transforming villages by building Georgian houses and Japanese bungalows. She goes overboard dreaming about how she can attempt to change society. We immediately sense, therefore, that she is destined to find that reality can never measure up to her dreams. While Carol's dreaminess may be one of her main character flaws, she still possesses many admirable traits, such as her enthusiasm for life and optimistic spirit.
In the preface to the novel, Lewis writes, "This is America—a town of a few thousand, in a region of wheat and corn and dairies and little groves. [Gopher Prairie's] Main Street is the continuation of Main Streets everywhere." In Main Street, therefore, Gopher Prairie represents a microcosm of America in the early 1900s, as Lewis creates many characters as caricatures or types rather than as individuals. For many Americans in the early 1900s, the "Norman Rockwell" image of small-town America represented the best aspects of the nation's culture. However, Lewis satirizes such an image of small-town America throughout the novel. To him, Gopher Prairie represents the narrow- mindedness and old-fashioned conservatism of America. Carol, on the other hand, embodies the spirit of the Progressive movement in America in the early 1900s, under the banner of which many people took an interest in social issues, such as the labor movement and women's rights movement. Carol, in short, represents change. It is not surprising, then, that throughout the novel she finds herself out of place in Gopher Prairie—a place that resists change.
In Chapter 3, Lewis highlights the differences between Carol's and Kennicott's perceptions. While Carol sees the people on the train as poor and ignorant, Kennicott sees them as content and well off. Carol takes an interest in aesthetics while Kennicott interests himself in material things. Throughout the novel, we see that Kennicott does not feel the need for change like Carol does. The two characters, then, represent the two major groups of people in America in the early 1900s: those who supported change and those who resisted it. While perhaps the primary theme in Main Street regards Carol's rebellion against Gopher Prairie, the secondary theme of marriage examines the realities and compromises of marriage—compared to the illusions of romance—throughout the novel.