Well, they did have to move Mulder somewhere...
http://www.pwcecondev.org/federal-agencies-corporate-facilities
Intro from the link:
Prince William County has a burgeoning federal, defense and security industry community, proudly serving as long-time home to the Marine Corps Base Quantico, the Marine Corps Warfighting Laboratory, the National Institute of Health Biomedical Research Laboratory, the FBI Northern Virginia Resident Agency, the Virginia Department of Forensic Sciences Laboratory and a number of General Services Administration (GSA) facilities. Ground-breaking research in proteomics, forensics and biodefense is part of Prince William County’s DNA.
Considering current events, couldn't help but notice the FBI Agency.
Well, they did have to move Mulder somewhere...