United States Department of Defense United States Department of Defense The Department of Defense (DoD, USDOD, or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government concerned directly with national security and the United States Armed Forces. The department is the largest employer in the world, with nearly 1.3 million active duty servicemen and women as of 2016. Adding to its employees are over 826,000 National Guardsmen and Reservists from the four services, and over 742,000 civilians bringing the total to over 2.8 million employees. Headquartered at the Pentagon in Arlington, Virginia,
Arlington County, Virginia 2018 ParkScore ranking of the top 100 park systems across the United States, according to the ranking methodologies of the nonpartisan Trust for Public Land. The climate in this area is characterized by hot, humid summers and generally mild to cool winters. According to the Köppen Climate Classification system, Arlington County has a humid subtropical climate, abbreviated "Cfa" on climate maps. As of the 2010 census, there were: The population density was 8,309 people per square mile (2,828/km²), the highest of any county in Virginia. According to the US Census, the racial makeup of the county in 2012 was: There