O Pioneers! is a work of literary realism. Realism became popular toward the end of the 19th century and was often framed as a reaction to sentimental fiction. Sentimental fiction, such as Harriet Beecher Stowe's Uncle Tom's Cabin and William Hill Brown's The Power of Sympathy, depicted highly dramatic situations and characters' over-the-top reactions to them. All this drama served to stir up the reader's emotions as well. By inviting the reader to sympathize with the plight of characters in dire situations, authors of sentimental novels often hoped to persuade readers into alignment with certain social and political causes. In the case of Uncle Tom's Cabin, for instance, Stowe hoped to turn readers against slavery. The idea behind using sentimentality for political purposes was that human emotions (especially sympathy) are universal. Social issues that seemed distant to many middle- and upper-class readers could come to seem more relevant if only these readers got excited about them.
Realism, by contrast, aims to get at quieter and more specific parts of human life. Works of realism are typically packed with details and images to help the reader imagine the highly individualized circumstances of characters' reality. In Part 1, Chapter 1 of Cather's novel, the narrator describes the details the reader would notice if they were to closely observe the streets in Hanover for a while:
The children were all in school, and there was nobody abroad in the streets but a few rough-looking countrymen in coarse overcoats, with their long caps pulled down to their noses. Some of them had brought their wives to town, and now and then a red or a plaid shawl flashed out of one store into the shelter of another.
The texture of the men's overcoats and the patterns on the women's shawls are details that would be unlikely to appear in a sentimental novel because they have nothing to do with the plot. But they make the setting of the novel come alive as a specific time and place, with specific fashions. The characters themselves may not notice such little details as they go about their lives, but the reader and narrator have the chance to slow down and pick apart the minutia of the fictional town.
By making Hanover and the Divide into a place with its own beauty and its own problems, distinct from the world most of the readers inhabit, Cather makes her characters less universally familiar than characters in a sentimental novel, but in many ways more realistic. Alexandra's problems are hers alone, but they are as complicated and subtle as any reader's own problems. Arguably, this subtlety makes for a novel that invites more nuanced reflection on political and social issues (such as immigration and labor) than a sentimental novel would. In fact, Cather emphasizes the world in which the characters live as such a powerful force in their lives that the novel can also be read as a work of naturalism. Closely related to realism, naturalism holds that a character's environment (natural and social) determines the course of their life. Cather's characters work toward self-determination, but they are ultimately all bound by their circumstances.
