Third Corps Area was a Corps Area of the United States Army, active from 20 August 1920–7 December 1941. It was established with its headquarters at Fort Howard, Maryland and organized from elements of the deactivated Eastern Department. The headquarters moved to Baltimore on 12 May 1922. It covered the states of Pennsylvania, Maryland, Virginia, and the District of Columbia. At is height, the Third Corps Area had 60,548 soldiers in 1943.