 During a Memorial Day trip, we went to the Reagan Library in California, and it was so cool to see his Air Force One and limo at the museum. Here at Greenfield Village, they have the presidential vehicle section with cars used by FDR, Truman, Eisenhower, Ford, Carter, Reagan, Bush, even the 1961 Lincoln Continental that JFK was shot in and Johnson had it rebuilt for him and then Nixon. I find presidential limos so interesting as FDR was the first to use an armored vehicle that had belonged to gangster Al Capone. But why did they stop using Lincolns and move to Cadillac?