The United States Army is the largest and oldest established branch of the armed forces of the United States and is one of seven uniformed services. Like all armies, it has the primary responsibility for land-based military operations.

The modern Army had its roots in the Continental Army which was formed on June 14 1775, before the establishment of the United States, to meet the demands of the American Revolutionary War. Congress created the United States Army on June 14 1784 after the end of the war to replace the disbanded Continental Army. The Army considers itself to be descended from the Continental Army, and thus dates its inception from the origins of that force.

Control and operation of the Army is administered by the Department of the Army, one of the three service departments of the Department of Defense. The civilian head is the Secretary of the Army and the highest ranking military officer in the department is the Chief of Staff. As of August 31, 2007, the Regular Army reported a strength of 519,471 soldiers. By the end of 2006, the Army National Guard (ARNG) reported 346,288 and the United States Army Reserve (USAR) reported 189,975, putting the approximate combined component strength total at 1,055,734.