The fact that Thurber wrote "An American Romance" at one short sitting was an anomaly. Normally, he spent enormous amounts of time perfecting his writing; many works remained unfinished for years. To some extent the writer's commitment of time to his work helps to explain his success. Thurber's style is his trademark. It is above all readable. Perhaps because his pieces are short they hold the reader's attention. (In spite of his several attempts to write a novel — one of which resulted in his spending "a thousand hours" on a 20, 000-word book that went through twenty to thirty rewrites over a period of two years yet was never published — he did not complete a novel because he could not sustain a reader's interest over such a length.) Thurber was meticulous and precise in word choice, and as a result his prose flows. It is relaxed and subtle, not at all harsh and haranguing. His remarkable memory allowed him to recall conversations exactly and thus realistically, and his attention to detail gave his stories a further solid, realistic feel. As was true of other practitioners of basically journalistic humor, Thurber's writing is paradoxical in that it contains the oral quality of the best yarn spinners of the nineteenth century while it simultaneously reflects an appreciation for the way that words appear on the printed page. The leisurely storytelling may be traced back to Henry James, who Thurber admits influenced his style, although the humorist also claims that he had to overcome that influence too. Thurber's love of the physical appearance of printed words is evident in The Wonderful O (1957), for example, and when he notes that the word "reason" is six-sevenths of the word "treason." Elsewhere he has commented, "I liked the shape of words and phrases, and I liked clean copy. I never turned in a page with a single mistake on it. I always copied it over. Naturally, when you copy you make changes and you improve your copy."
Historically, Thurber follows the traditional horse-sense humorists, and he is clearly related to the nineteenth and early twentieth-century journalistic humorists and literary comedians such as Mark Twain, George H. Derby (who wrote "A New System of English Grammar"), Robert Henry Newell, Charles Farrar Browne, David Ross Locke, Henry W. Shaw, Charles H. Smith, Edgar Wilson Nye, George Ade (the author of a series of Fables in Slang), Finley Peter Dunne, Ambrose Bierce, and Ring Lardner, among others, who commented from an objective point of view on the contemporary world that surrounded them and in a very specific format. Thurber's Little Man character draws from Benchley, and perhaps later from S. J. Perelman a bit, but he is at the beginning of a tradition, and ultimately his refinements make the character uniquely and identifiably his own creation.