How did Edgar Allan Poe influence American Romanticism?

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.

Edgar Allen Poe was one of the most influential and prolific writers of the Romantic Period. The Romantics were reacting against the Enlightenment, which was a literary (among other things) movement concentrating on rationality and reason as the most valuable tool for humans to understand the world. The Romantics, on the other hand, rejected the notion that everything could be understood with the mind, and preferred to write about the supernatural and irrational. They were more attracted to the animal, emotional side of humans and the dark, unknowable side of the universe. Horror became very popular, as well as dark fantasy.

That said, Edgar Allen Poe's writing is one of the most perfect examples of this ethos. "The Cask of Amontillado" is a tale of irrational revenge—the protagonist is seeking to murder a man for a perceived insult. Likewise, the exploration of terror in "The Pit and the Pendulum" is a good example of Poe showing how the human mind is not a perfectly rational machine. In general, Poe's explorations of madness are exemplify the Romantic period, because showing how human rationality can fail was a primary goal of the movement. Finally, in poems like "The Raven" and "Annabel Lee," the concept of mourning for a lost lover is an expression of grief and despair that is typical of the Romantics—they were intrigued by death and loss, in opposition to the Enlightenment, which tried to be constructive and positive. 

What is the connection between Edgar Allan Poe and the Romantic Era?

Edgar Allan Poe is usually considered an example of the Romantic movement in the United States. Although his publications are slightly later than those of such well known British Romantics as Shelley, Byron, and Wordsworth, his works share many of their characteristics. 

Although his detective stories form a separate class of works with fewer overtly Romantic characteristics, his poetry and other short fiction is typical of the movement. 

First, his settings are often Gothic in style, rugged, decayed, mysterious, ominous, isolated, or otherwise suggesting a sensibility steeped in exoticism. Like other Romantics, his works are intended to convey a mood as much as narrate a complex plot, and tends towards the melancholy and melodramatic. He is master of building atmosphere, especially of horror or madness. His works eschew moral lessons, and follow a dictate of art for art's sake, looking forward to and influencing the decadent movement towards the end of the century.

He influenced the development of the short story and of horror and mystery in both the United States and France, where his works were especially popular.