Franklin Delano Roosevelt had travelled across the depression-ravaged US on trains to pitch his 'New Deal' to voters in the 1930s.
But with World War II raging, his security team in 1942 decided that he needed a specially designed car to defend his security.
They commissioned famed train maker Pullman to redesign for the president's exclusive use one of the six private carriages it had available, all named after famous explorers.
The Ferdinand Magellan after the redesign was also known as US Car No 1.
It was encased in layers of half-inch thick nickel plated armor, and bullet-proof windows. Its undercarriage was strengthened, in case would-be assassins planted bombs on the rail track.
With Roosevelt disabled by polio, it was also redesigned to allow him to access all parts of the carriage in his wheelchair.
There were also two secret escape hatches, through which the president could be hauled in case of an emergency.
The redesign doubled its weight to 285,000 pounds — heavier than a tank.
Source: White House Historical Association