 501st Infantry Regiment (United States)

The 501st Airborne Infantry Regiment (501st AIR), previously the 501st Parachute Infantry Regiment (501st PIR) and later 501st Infantry Regiment (501st IR), is an airborne forces regiment of the United States Army, with a long history, having served in World War II and the Vietnam War, both as part of the 101st Airborne Division, as well as the War in Afghanistan.It is the first airborne unit by designation in the United States Armed Forces.