The main settings of The Custom of the Country are New York and Paris, but the economic center is Apex City, Kansas. During the course of the novel, fortunes are made and lost in Apex City, and the winners of these fortunes spend their money in New York and Paris. Although no scenes take place in Apex City, what happens there determines much of the action in the other locations.

The natives of Apex City possess the classic American virtues of self-reliance, seemingly boundless energy, and business opportunism: Undine Spragg moves from Apex City to New York and then Paris with the aim of finding a place at the top of the social ladder while Elmer Moffatt goes from penniless young man to the world's greatest collector, capable of raising the price of pearls by fifty percent when he decides to buy them. These characters possess...