Harford County is a county located in the U.S. state of Maryland. As of the 2020 census, the population was 260,924. Its county seat is Bel Air. Harford County is included in the Baltimore-Columbia-Towson, MD Metropolitan Statistical Area, which is also included in the Washington-Baltimore-Arlington, DC-MD-VA-WV-PA Combined Statistical Area.

Aberdeen Proving Ground (APG) is a U.S. Army facility located adjacent to Aberdeen, Harford County, Maryland, United States. More than 7,500 civilians and 5,000 military personnel work at APG. There are 11 major commands among the tenant units, including:United States Army Communications-Electronics Command (CECOM) United States Army Combat Capabilities Development Command (CCDC) United States Army Test and Evaluation Command (ATEC) Edgewood Arsenal Adelphi Laboratory Center The Army Reserve Information Operations Command Unified Cross Domain Services Management Office HQ, U.S. Army Contracting Command U.S Army 93rd Signal Network - Network Enterprise Center Logistics Readiness Center U.S. Army Cyber Operation Group – 335th Signal Command Blossom Point Research Facility