According to Elements of Literature: Literature of the United States, a high school textbook published by Holt, Rhineholt and Winston, the period of American Romanticism was from 1800-1860; however, there is another term in this text that applies to American literature after 1850. That period is termed the American Renaissance. It was during this period that writers such as Ralph Waldo Emerson, Henry David Thoreau, Nathaniel Hawthorne, and Herman Melville wrote some of "the early masterpieces of American literature."
Emerson and Thoreau were Transcendentalists, a much more religious movement involving the goal of "transcending" life, experiencing knowledge through intuition. Romanticism also held a love for the spiritual, but, above all, this literary movement held that love and worship for nature was the source of inspiration. Transcendentalists viewed nature "as a doorway to a mystical world holding important truths." They sought an "inner light," not knowledge through nature.
Ironically, many people consider Hawthorne, Melville, and Edgar Allan Poe as anti-Transcendentalists since their view of the world was much more pessimistic than that of the optimistic Emerson, Thoreau, and their followers. However, the works of what many call these Dark Romantics shared with the Transcendentalists their sense of value in intuition and spontaneous feelings over logic and reason. But their dark perspective of the world offered a counterpoint to both the Transcendentalists and the Romantics. These Dark Romantics (Hawthorne, Melville, and Poe) did not ignore the more melancholic aspects of man's soul and the darkness of Puritan and Calvinistic notions as the Romantics did. This, then, may be the most salient difference in the Romantic movement of the earlier nineteenth century and the changes in mid-nineteenth century literature.
Additional source: Elements of Literature:Literature of the United States. New York: Holt, Rhinehart and Winston, 2000. Print.