American Romanticism began in the 1820s as a reaction against Enlightenment rationalism, placing new emphasis on emotion, nature, imagination, and the supernatural. Key characteristics included an appreciation of nature's beauty, a belief in humanity's inherent goodness, and the concept of the Romantic hero as intuitive and close to nature. The movement saw works produced by early American writers like Irving, Cooper, Bryant, and Longfellow before the Civil War ended the Romantic period and ushered in Realism. Dark Romantics like Poe, Hawthorne, and Melville acknowledged humanity's capacity for evil.