I think that one could argue that Poe's impact on American Romanticism was significant because it sought to explore a potential dark side to emotions. Poe was instrumental in exploring a darker aspect to human expression. The growth of American Romanticism and Transcendentalism asserted a very positive aspect to the human condition. In contrast to British Romanticism and its American counterpart in Transcendental thought, Poe was able to illuminate another side to it. He was able to access the darker and potentially more malevolent nature that existed as part of the human condition. Poe affects American Romanticism because he taps into the Germanic Romanticism that explored philosophical and metaphysical condition. Bringing light to this philosophical condition is where Poe's contribution to American Romanticism is evident. Without Poe and the tales he weaves, American Romanticism misses a vital part of what the human being can be as opposed to a hopeful assertion of what should be.
Another way in which Poe impacted the American Romantic movement is through his use of the short story. Poe was able to define that the artist did not need to embrace the novelized approach to literature in order to connect with the audience. Poe understood the Romantic tradition of an artist defining their own aesthetic condition. In the short story that Poe utilized, he was able to expand the condition of American Romanticism. As a Romantic artist, Poe was able to use his short story approach as a way to connect with the audience and, in doing so, expand the literary aesthetic of what might be. This is Romantic in nature and becomes one of Poe's significant contributions to American Romanticism.
Poe's ability to transform the writing capacity of the author both in aesthetics and themes helped to enhance American literature and expand American Romanticism. At a time when the volume of intellectual and creative production was residing in Europe in Germanic, French, and English traditions, American Romanticism was fledgling. Poe's contributions were able to move American Romanticism in the same terrain as its European counterparts. The volumes of work that Poe was able to produce enabled American Romanticism to gain a sense of depth and intellectual formidability with those in the Europe. This becomes one of the most significant ways in which Poe affected American Romanticism.