NAVAIR and it's associated contractors represent the largest employment sector in St. Mary's County. People who work at the various NAVAIR facilities live in Calvert, Charles and St. Mary's County.

In Calvert County, the largest employer is the Calvert Cliffs Nuclear Power Plant. Residents of Calvert also work in the district and at the NAVAIR facilities in St. Mary's.

The largest employer in Charles county is the Naval Surface Warfare Center in Indian Head. Residents of Charles County work in many diverse facilities in close proximity such as NAVAIR in St. Mary's; the Navy Proving Grounds across the Potomac River in Dahlgren, Va; Andrews Air Force in nearby Prince George's County and Washington, D.C.