FILE - In this June 14, 1961 file photo, U.S. Secret Service agents stand on retractable stands on President John F. Kennedy's new plastic-topped Lincoln Continental limousine outside the White House, after its delivery in Washington. The car has three roof combinations, a rear seat that can be raised and lowered, retractable foot stands for Secret Service men, two two-way radio telephones, and a master control panel for power accessories. (AP Photo/Henry Burroughs, File)