"Sacred Cow" was the first aircraft specifically built to fly the President of the United States.

When the idea of flying President Franklin Roosevelt in a C-87 Liberator Express was considered dangerous (The C-87 had a tendency to just explode and break apart in flight), the US government turned to the Douglas DC-4, being built in huge numbers as the C-54 Skymaster for the USAAF. Taking a C-54A, Douglas installed wings of the C-54B on the aircraft to give it longer range. In fact the forward fuselage has two large fuel tanks installed to give even longer range. Christened "Sacred Cow", the rather plain, inconspicuous VC-54C had a furnished interior that could fit 20 people, including a presidential office space, galley, and lounge. It was modified to include a small electric elevator to hoist Roosevelt on and off, as the president was parallelized from polio in his youth.

Ironically, Sacred Cow only flew Roosevelt once, on the important meeting at Yalta with Churchill and Stalin in early 1945. After Roosevelt's sudden death from a stroke, Sacred Cow was used by president Harry S. Truman for the first 27 months of his administration. Unpressurized, slow, and wearing out President Truman sought a replacement, which was found in the successor Douglas DC-6, which became "The Independence" in late 1947. Sacred Cow continued to fly as a VIP plane until retired to the NMUSAF in 1961, flown by Roosevelt's own pilot during the Second World War.