Military branches:
United States Armed Forces: US Army, US Navy (includes Marine Corps), US Air Force, US Coast Guard; note - Coast Guard administered in peacetime by the Department of Homeland Security, but in wartime reports to the Department of the Navy (2009)
Military service age and obligation:
18 years of age (17 years of age with parental consent) for male and female voluntary service; maximum enlistment age 42 (Army), 27 (Air Force), 34 (Navy), 28 (Marines); service obligation 8 years, including 2-5 years active duty (Army), 2 years active (Navy), 4 years active (Air Force, Marines) (2008)
Manpower available for military service:
males age 16-49: 72,715,332
females age 16-49:
71,638,785 (2008 est.)
Manpower fit for military service:
males age 16-49: 59,764,677
females age 16-49:
59,437,663 (2009 est.)
Manpower reaching militarily significant age annually:
male: 2,196,124
female:
2,085,085 (2009 est.)
Military expenditures:
4.06% of GDP (2005 est.)
