The United States Army Military District of Washington (MDW) is one of nineteen major commands of the United States Army. Its headquarters are located at Fort Lesley J. McNair in Washington, D.C. The missions of the units in the Military District of Washington include ceremonial tasks as well as a combat role in the defense of the National Capital Region.

Fort Lesley J. McNair, also historically known as the Washington Arsenal, is a United States Army post located on the tip of Buzzard Point, the peninsula that lies at the confluence of the Potomac River and the Anacostia River in Washington, D.C. To the peninsula's west is the Washington Channel, while the Anacostia River is on its south side. The fort has been an army post for more than 200 years, third in length of service, after the United States Military Academy at West Point and the Carlisle Barracks. The fort is named for General Lesley James McNair, who was killed in action by friendly fire in Normandy, France during World War II.