why is "the legend of sleepy hollow" referred to as romantic

Washington Irving came before the Romantic Period. Many felt that he paved the way for later romantic literature of the late 1800's. Many of the themes in Sleepy Hollow can be found in the writings of authors like Shelley (Frankenstein) and Poe (Tell Tale Heart). Much of its Gothic nature, which is very much the substance of Sleepy Hollow, was used heavily during the Romantic period. Themes like good vs evil, the supernatural and fear of the unknown define Sleepy Hollow. So, although this story is not truly part of the Romance Period it was certainly was a prelude to it.