The Mount Airy Historic District is a national historic district in Mount Airy, located in Carroll and Frederick County, Maryland. The district comprises a cohesive group of commercial, residential, and ecclesiastical buildings dating from the late 19th through early 20th centuries. The brick Baltimore and Ohio Railroadstation, constructed in 1882, represents the town's origin as an early transportation center for the region, which dates back as early as 1838. A group of early-20th century commercial structures represent the rebuilding of Mount Airy's downtown after a series of fires between 1903 and 1926. The residential areas are characterized by houses illustrating vernacular forms and popular stylistic influences of the late 19th and early 20th century. Three churches are located within the district.