"The chief responsibility of the U.S. Secret Service is to guard the life of the President... In Dallas, on November 22, a sniper hidden in an office building shot and killed President John F. Kennedy... It was the first time since the Secret Service took over its protective mission 62 years ago that a President had been harmed. Guarding the President has become more and more of a problem in recent years...Presidents travel a lot more - at home and abroad - and are frequently exposed to big crowds."
