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

Aberdeen is a city located in Harford County, Maryland, United States, 26 miles (42 km) northeast of Baltimore. The population was 16,254 at the 2020 United States Census. Aberdeen is the largest municipality in Harford County.