Science-fiction and fantasy magazines began to be published in the United States in the 1920s. Stories with science-fiction themes had been appearing for decades in pulp magazines such as Argosy, but there were no magazines that specialized in a single genre until 1915, when Street & Smith, one of the major pulp publishers, brought out Detective Story Magazine. The first magazine to focus solely on fantasy and horror was Weird Tales, which was launched in 1923, and established itself as the leading weird fiction magazine over the next two decades; writers such as H.P. Lovecraft, Clark Ashton Smith and Robert E. Howard became regular contributors. In 1926 Weird Tales was joined by Amazing Stories, published by Hugo Gernsback; Amazing printed only science fiction, and no fantasy. Gernsback included a letter column in Amazing Stories, and this led to the creation of organized science-fiction fandom, as fans contacted each other using the addresses published with the letters. Gernsback wanted the fiction he printed to be scientifically accurate, and educational, as well as entertaining, but found it difficult to obtain stories that met his goals; he printed "The Moon Pool" by Abraham Merritt in 1927, despite it being completely unscientific. Gernsback lost control of Amazing Stories in 1929, but quickly started several new magazines. Wonder Stories, one of Gernsback's titles, was edited by David Lasser, who worked to improve the quality of the fiction he received. Another early competitor was Astounding Stories of Super-Science, which appeared in 1930, edited by Harry Bates, but Bates printed only the most basic adventure stories with minimal scientific content, and little of the material from his era is now remembered.
In 1933 Astounding was acquired by Street & Smith, and it soon became the leading magazine in the new genre, publishing early classics such as Murray Leinster's "Sidewise in Time" in 1934. A couple of competitors to Weird Tales for fantasy and weird fiction appeared, but none lasted, and the 1930s is regarded as Weird Tales' heyday. Between 1939 and 1941 there was a boom in science-fiction and fantasy magazines: several publishers entered the field, including Standard Magazines, with Startling Stories and Thrilling Wonder Stories (a retitling of Wonder Stories); Popular Publications, with Astonishing Stories and Super Science Stories; and Fiction House, with Planet Stories, which focused on melodramatic tales of interplanetary adventure. Ziff-Davis launched Fantastic Adventures, a fantasy companion to Amazing.Astounding extended its pre-eminence in the field during the boom: the editor, John W. Campbell, developed a stable of young writers that included Robert A. Heinlein, Isaac Asimov, and A.E. van Vogt. The period starting in 1938, when Campbell took control of Astounding, is often referred to as the Golden Age of Science Fiction. Well-known stories from this era include Slan, by van Vogt, and "Nightfall", by Asimov. Campbell also launched Unknown, a fantasy companion to Astounding, in 1939; this was the first serious competitor for Weird Tales. Although wartime paper shortages forced Unknown's cancellation in 1943, it is now regarded as one of the most influential pulp magazines.
Only eight science-fiction and fantasy magazines survived World War II. All were still in pulp magazine format except for Astounding, which had switched to a digest format in 1943. Astounding continued to publish popular stories, including "Vintage Season" by C. L. Moore, and "With Folded Hands ..." by Jack Williamson. The quality of the fiction in the other magazines improved over the decade: Startling Stories and Thrilling Wonder in particular published some excellent material and challenged Astounding for the leadership of the field. A few more pulps were launched in the late 1940s, but almost all were intended as vehicles to reprint old classics. One exception, Out of This World Adventures, was an experiment by Avon, combining fiction with some pages of comics. It was a failure and lasted only two issues. Magazines in digest format began to appear towards the end of the decade, including Other Worlds, edited by Raymond Palmer. In 1949, the first issue of The Magazine of Fantasy and Science Fiction appeared, followed in October 1950 by the first issue of Galaxy Science Fiction; both were digests, and between them soon dominated the field. Very few science-fiction or fantasy pulps were launched after this date; the 1950s was the beginning of the era of digest magazines, though the leading pulps continued until the mid-1950s, and authors began selling to mainstream magazines and large book publishers.
Ralph 124C 41+, by Hugo Gernsback, serialized in Modern Electrics in 1912
By the end of the 19th century, stories with recognizably science fictional content were appearing regularly in American magazines.[note 1] These magazines typically did not print fiction to the exclusion of other content; they would include non-fiction articles and poetry as well. In October 1896, the Frank A. Munsey company's Argosy magazine was the first to switch to printing only fiction, and in December of that year it began using cheap wood-pulp paper. This is now regarded by magazine historians as having been the start of the pulp magazine era.[note 2] For twenty years the pulps were successful without restricting their fiction content to any specific genre, but in 1915 the influential magazine publisher Street & Smith began to issue titles that focused on a particular niche, such as Detective Story Magazine and Western Story Magazine, thus pioneering the specialized and single-genre pulps.
As the pulps proliferated, they continued to carry science fiction (sf), both in the general fiction magazines such as Argosy and All-Story, and in the more specialized titles such as sports, detective fiction, and (especially) the hero pulps. Science fiction also appeared outside the world of pulps: Hugo Gernsback, who had begun his career as an editor and publisher in 1908 with a radio hobbyist magazine called Modern Electrics, soon began including articles speculating about future uses of science, such as "Wireless on Saturn", which appeared in the December 1908 issue. The article was written with enough humour to make it clear to his readers that it was simply an imaginative exercise, but in 1911 Modern Electrics began serializing Ralph 124C 41+, a novel set in the year 2660. In 1913 Gernsback launched another magazine, The Electrical Experimenter (retitled Science and Invention in 1920), which frequently ran science fictional tales, written both by Gernsback and others.
In 1919, Street & Smith launched The Thrill Book, a magazine for stories that were unusual or unclassifiable in some way, which in most cases meant that they included either fantasy or science-fiction elements.[note 3][note 4]The Thrill Book ceased publication in October 1919, having lasted sixteen issues; it carried some sf, particularly towards the end of its short run, but is not generally regarded as a science-fiction or fantasy pulp. Two years later, Gernsback launched yet another magazine, titled
Practical Electrics, and in 1924 he sent a letter to its subscribers suggesting a magazine that would publish only scientific fiction. The response was weak, and Gernsback shelved the project.