Hybla Valley is a census-designated place (CDP) in Fairfax County, Virginia, United States, south of Alexandria. The population was 15,801 at the 2010 census,[3] down from 16,721 in 2000 due to a reduction in area, resulting from some of the eastward neighborhoods including much of Hollin Hills being moved to the Fort Hunt CDP.[1]

The Mason family’s Hollin Hall plantation, just south of Alexandria, had become the property of several owners, including Edward Curtis Gibbs and the Wilson family. Thomson Dairy had been founded on the land in the late 19th century, and lasted until Merle Thorpe purchased it in the early 20th century.[citation needed] The various dairy farms, such as Sherwood Farm, Hybla Valley Farm, and Popkins Farm were converted into suburban neighborhoods, while plans for the construction of the George Washington Air Junction and the Hybla Valley Airport began. The civilian airport was proposed to be the largest in the world, yet the land, which had once been dairy farm, was abandoned and is currently Huntley Meadows Park. During World War II, the famous Hollin Hills subdivision, to the east of U.S. Route 1 towards the Potomac River, was completed by designers Charles Goodman and Robert Davenport. Also during the war, the princess of Norway sought refuge from the conflict in Europe and wished to purchase the property of Hollin Hall; President Roosevelt personally inspected the land for her, yet his assistant, Thorpe, became its new owner in the end. The land surrounding it became a turkey farm, and was eventually bought by the Mount Vernon Unitarian Church. In 1978, the Mount Vernon Unitarian Church donated land within Hollin Hills to create the wealthy Mason Hill subdivision. Although still starkly different from the affluent section of the CDP, the west side of Hybla Valley has developed over the years, including the up-scale and modern Mount Vernon Plaza in 2002.