Despite that it was formed on the day of President Lincoln's assassination, the Secret Service has only been working at presidential inaugurations since 1885. Early on, their role was to help local police stop small crimes along the parade route and to keep people from “annoying” the president, while military and police officers were responsible for guarding the president. It was not until 1902 that the Secret Service provided full-time protection for the president of the United States.
In the first years of this new assignemnt, only the president received Secret Service protection. In 1913, this was expanded to include the president-elect. The president’s immediate family was added to the list of those protected by the Secret Service in 1917, and the vice president was added in 1951.
As a result of Robert Kennedy’s assassination during the 1968 presidential election campaign, major presidential and vice presidential candidates and nominees also joined that list.