When the novel was published on March 14, 1939, 50,000 copies were on order, a remarkable number for a Depression-era book. By the end of April, The Grapes of Wrath was selling 2,500 copies a day. By May, it was the number-one bestseller and was selling 10,000 copies a week. At the end of the year, close to a half-million copies had been sold. It was the top seller of 1939 and remained a best-seller throughout 1940. Since then, the novel has been continuously in print.

Despite its overwhelming popularity, the novel did not receive only favorable reviews. Journalists who wrote early reviews in the newspapers were not particularly impressed with the book. Steinbeck had broken many of the “rules” of fiction writing with his novel. Several reviewers could not understand the novel’s unconventional structure. In Newsweek, Burton Roscoe wrote that the book has some “magnificent passages” but that it also contains factual errors (including statements that the Dust Bowl extended into eastern Oklahoma when that region of the state had actually remained fertile) and misleading propaganda. A reviewer in Time magazine criticized the chapters that did not describe the Joads’ story, saying they were “not a successful fiction experiment.” In the New Yorker, Clifton Fadiman wrote that the novel “dramatizes so that you cannot forget the terrible facts of a wholesale injustice committed by society,” yet he also wrote that the latter half of the book was “too detailed.”

Similarly, other critics found fault with the structure of the novel. Louis Kronenberger in the Nation and Malcolm Cowley in the New Republic criticized the latter half of the book and particularly the ending. Other magazine reviewers, especially those writing for monthlies and literary quarterlies, did not focus entirely on the sociological aspects of the novel and considered its artistic merit. These reviewers, on the whole, recognized that Steinbeck had written a seminal and innovative novel. The editor of the Atlantic Monthly, Edward Weeks, wrote that it was a “novel whose hunger, passion, and poetry are in direct answer to the angry stirring of our conscience these past seven years.” Weeks found the novel almost “too literal, too unsparing,” yet he could “only hope that the brutality dodgers will take my word for it that it is essentially a healthy and disciplined work of art.”

In the North American Review, Charles Angoff defended the novel: “With his latest novel, Mr. Steinbeck at once joins the company of Hawthorne, Melville, Crane and Norris, and easily leaps to the forefront of all his contemporaries. The book has all the earmarks of something momentous, monumental, and memorable. . . . The book has the proper faults: robust looseness and lack of narrative definiteness— faults such as can be found in the Bible, Moby-Dick, Don Quixote, and Jude the Obscure. The greater artists almost never conform to the rules of their art as set down by those who do not practice it.”

One early reviewer who summed up the novel’s greatness was Joseph Henry Jackson in the New York Herald Tribune Books. Jackson was the book editor of the San Francisco Chronicle and had followed Steinbeck’s career. He wrote in his review of April 16, 1939, that the novel was the finest book that Steinbeck had written. The review stated: “It is easy to grow lyrical about The Grapes of Wrath, to become excited about it, to be stirred to the shouting point by it. Perhaps it is too easy to lose balance in the face of such an extraordinarily moving performance. But it is also true that the effect of the book lasts. The author’s employment, for example, of occasional chapters in which the undercurrent of the book is announced, spoken as a running accompaniment to the story, with something of the effect of the sound track in Pare Lorentz’s The River—that lasts also, stays with you, beats rhythmically in your mind long after you have put the book down. No, the reader’s instant response is more than quick enthusiasm, more than surface emotionalism. This novel of America’s new disinherited is a magnificent book. It is, I think for the first time, the whole Steinbeck, the mature novelist saying something he must say and doing it with the sure touch of the great artist.”