Organizational structure of the United States Department of Defense of the Treasury. According to the U.S. Code, the Coast Guard is at all times considered one of the five armed services of the United States. During times of declared war (or by Congressional direction), the Coast Guard operates as a part of the Navy; this has not happened since World War II, but members have served in undeclared wars and conflicts since then while the service remained in its peacetime department. The Pentagon, in Arlington County, Virginia, across the Potomac River from Washington, D.C., is the Department's headquarters. The Department is protected by the Pentagon Force Protection Agency, which
Arlington County, Virginia Arlington County, Virginia Arlington County is a county in the Commonwealth of Virginia, often referred to simply as Arlington or Arlington, Virginia. In 2016, the county's population was estimated at 230,050, making it the sixth-largest county in Virginia, or the fourth-largest city if it were incorporated as such. It is the 5th highest-income county in the U.S. by median family income, and has the highest concentration of singles in the region. The county is coterminous with the U.S. Census Bureau's census-designated place of Arlington. Though a county, it is also treated as the second-largest principal city of the Washington metropolitan