Quantico is a town in southeastern Prince William County, Virginia, United States. The population was 578 at the 2020 census. Quantico is approximately 35 miles southwest of Washington, D.C., bounded by the Potomac River to the east and the Quantico Creek to the north. The word 'Quantico' is a corruption of the name of a Doeg village recorded by English colonists as Pamacocack.