Frederick, city (1990 pop. 40,148), seat of Frederick co., NW Md.; settled 1745, inc. 1817. The processing center of a fertile farm and dairying area, it makes beer, household items, optical and glass products, leather goods, clothing, and electronic equipment. The largest employer, however, is Fort Detrick, a U.S. Army medical research center. Frederick was an important grain-trading center and a stop on the road west to the Ohio valley. In the Civil War, Confederate troops passed through the city en route to the battle of Antietam (see Antietam campaign). Points of interest include the grave of Francis Scott Key, author of "The Star-Spangled Banner," and the house of Barbara Frietchie, legendary Civil War heroine. Hood College and the Maryland School for the Deaf are in Frederick. The Monocacy National Battlefield is nearby.