Marine One is the call sign of any United States Marine Corps aircraft carrying the President of the United States. It usually denotes a helicopter operated by the HMX-1 "Nighthawks" squadron, either the large VH-3D Sea King or the newer, smaller VH-60N "WhiteHawk", both due to be replaced by the VXX program. A Marine Corps aircraft carrying the Vice President has the call sign Marine Two.
The first use of helicopters for presidential transport was in 1957, when Dwight D. Eisenhower traveled on an Bell UH-13J Sioux. The president needed a quick way to reach his summer home in Rhode Island; Air Force One was too large for such short trips, while traffic would be disrupted by traveling in a motorcade. Eisenhower instructed his staff to look into alternative modes of transportation; a Sikorsky UH-34 Seahorse helicopter was commissioned. The early aircraft lacked the "creature comforts" found on its modern successors, such as air conditioning and toilets.
In 1958, the H-13 was replaced by the Sikorsky H-34, and in 1961 by the VH-3A. Not long after the mode of presidential transport was introduced, presidential aides asked the Marines to look into the White House South Lawn as a helicopter landing zone. Ample room was present, and the protocol was established.