Dahlgren is an unincorporated community and census-designated place (CDP) in King George County, Virginia, United States.

In 2006, it was renamed "Naval Support Activity-South Potomac (NSA-SP)", with NSWCDD becoming a tenant command of the base.

Naval Space Surveillance Systems command was located at that base, but that responsibility was transferred to the Air Force in 2004.

The Dahlgren CDP extends north to state route 635, to the west to the unincorporated community of Owens, and south to the tidal Upper Machodoc Creek, an arm of the Potomac.

As of the 2010 census[1] the population had more than doubled, although the makeup was largely the same, with whites edging down as a percentage from 70.31% to 61.4%, blacks up from 25.28% to 30.5%, Hispanics up from 1.71% to 4.1%, and those reporting mixed race up from 1.91% to 3.8%.

It promotes the history, traditions, heritage, and culture of the U.S. Navy at Dahlgren, Virginia and the surrounding community.

Its key holdings include a scale model of a Civil War-era Dahlgren gun, the propeller from the first radio-controlled, unmanned flight, and Norden bombsight.

[8] The Raptor Challenge is a roadside attraction, where visitors try to locate the statues of Velociraptors along route 301.