Frightening or supernatural tales were an early staple of American literature. For the first European settlers in the strange new world, tasked with eking out an existence in the wilderness and forced to contend with attacks from Native Americans, threats were numerous and real. Moreover, the strict religious faith of the Puritans - which argued for the existence of life after death as well as a range of supernatural beings - gave rise to fears of supernatural threats as well. Bierce was influenced by a number of early American writers, and in turn influenced many others.
Perhaps the earliest American horror story was "The Legend of Sleepy Hollow" by Washington Irving (born 1783). "Sleepy Hollow" tells the tale of eccentric Ichabod Crane, who tries to woo the lovely Katrina Van Tassel, only to find himself pursued by a dark, headless figure, supposedly the ghost of a Hessian who died during a war.
Nathaniel Hawthorne (born 1804) is perhaps most famous for The Scarlet Letter, but wrote a number of stories influenced by the supernatural. The House of Seven Gables, for example, describes the effect of an ancestral curse in Salem, Massachusetts.
The most foundational figure in the history of American horror is Edgar Allen Poe (born 1809). Poe's great works include the poem "The Raven" and the short stories "The Tell-Tale Heart," "The Fall of the House of Usher," and "The Masque of the Red Death." Poe pioneered the eerie in his work, and focused more on the psychological qualities of his character than prior writers.
Charlotte Perkins Gilman (1860), best known for her suffragist activism, made a major contribution to American horror with "The Yellow Wallpaper," the tale of a woman who is essentially imprisoned by her husband and doctor, and who gradually goes insane.
Bierce also influenced later writers as well. HP Lovecraft (1890) in particular points to Bierce's stories as excellent examples of the weird tale and especially praises his twist endings. In the modern era, Stephen King (1947) and Dean Koontz (1945) have frequently used Bierce's literary technique of twist endings.