Poe is best known as the author of numerous spine-tingling stories of horror and suspense. He should also be remembered, however, as the author who helped to establish and develop America’s one real contribution to the world of literature—the short-story form. Poe was the first writer to recognize that the short story was a different kind of fiction than the novel and the first to insist that, for a story to have a powerful effect on the reader, every single detail in the story should contribute to that effect. His stories and criticism have been models and guides for writers in this characteristically American genre up to the present time. No one who is interested in the short-story form can afford to ignore his ideas or his fiction.

Poe was influential in making American literature more philosophical and metaphysical than it had been heretofore, especially in terms of the dark Romanticism of Germany rather than the sometimes sentimentalized romanticism of New England Transcendentalists. Poe also helped to make periodical publishing more important in American literary culture. American writing in the mid-nineteenth century was often discouraged by the easy accessibility of English novels. Lack of copyright laws made the works of the great English writers cheaply available; thus, American writers could not compete in this genre. Periodical publishing, and the short story as the favored genre of this medium, was America’s way of fighting back. Poe was an important figure in this battle to make the United States a literary force in world culture.

- From enotes.com