Though the actual trip from the White House to Capitol Hill was short, Secret Service agents at the time were concerned about his personal safety. Standard vehicles had always been used to transport the President wherever he travelled; however now with the possibility of war pending, they thought a more secure and safer mode of transportation should be used.
Federal Laws in place at the time prohibited government agencies and departments from purchasing vehicles that cost more than $750. The only recourse the Secret Service had was to get emergency authority and funding from Congress to purchase a safer vehicle; however with all the mayhem erupting in Washington, nobody had time for that.
As luck would have it, one of the older (or should we say long-term) agents working for the Secret Service, remembered the US Treasury Department had seized a bulletproof car from a mobster a few years ago that might work.
The mobster they seized the vehicle from was none other than Al Capone - the famous Chicago crime boss. Capone, you may recall, was sent to prison in 1931 for tax evasion. He failed to file and pay taxes on $150,000 of income he earned from his illegal operations. The car the Treasury Department seized from Al Capone was now sitting in a Washington D.C. warehouse.
Capone’s seized car was a 1928 Cadillac Town Sedan which had a V-8 engine.
The point we should all remember from this fascinating little story is: The very first "Official" White House Limousine ever used to transport a US President was a bulletproof Cadillac, formerly owned by the notorious Chicago gangster, Al Capone.