for auction)

Historic: Still bearing the insignia of the presidential fleet, the plane is now sitting at the Phoenix/Mesa Gateway Airport as it awaits its future

For sale: Spanning the administration of six U.S. presidents, the plane was assigned to the 89th Airlift Wing at the Andrews Naval Air Facility in Maryland, from February 1975 to September 2005

Air Force One refers to the air traffic control sign of the Air Force plane that carries the president.

Democrat Franklin Delano Roosevelt was the first president to fly in an aircraft while in office.

Prior to the 1940s, rail was seen as the most effective mode of transport.

The concept of having a presidential plane began in 1943, when the military grew concerned over the safety of the president flying commercially during World War II.

PresidentRoosevelt was the first Commander-in-Chief to be transported on Air Force One, when he was flown in a C-54 Skymaster to the Yalta Conference in February 1945.

Modern: President Barack Obama is transported around on one of two Boeing VC-25As, a military version of the Boeing 747 airliner

Security: President Barack Obama, in Austin, Texas on May 9, primarily travels by air in the secure aircraft

The term 'Air Force One' was designated as the official air traffic control sign for the presidential aircraft in 1953.

Multiple planes in the presidential fleet have been used to carry the president.

In the sixties, the Air Force designated Boeing 707 as the primary plane for the president.

Since the 1990s, two Boeing VC-25As, a military version of the Boeing 747 airliner, have been used to carry