The 504th Infantry Regiment, known during World War II, as the 504th Parachute Infantry Regiment (504th PIR) was and still is a regiment of the 82nd Airborne Division of the United States Army.
The regiment was initially Constituted on February 24, 1942 in the Army of the United States as the 504th Parachute Infantry Regiment. It was activated on May 1, 1942 at Fort Benning, Georgia, and was assigned to the US Army Airborne Command. Having completed its Regimental training, it was assigned August 15, 1942 to the 82d Airborne Division.