Where was the secret service when Lincoln was shot?

The US Secret Service was in it's infancy and it began to mostly concentrate of counterfeite monies, and the like. President Garfielf was assassinated at a Washington, DC subway station; and President McKinley was shot in Buffalo, NY. His VP Theodore Roosevelt was vacationing as well in the Finger Lakes area. Upon hearing the President had been shot, the VP packed up everything and traveled the full distance to Buffalo. The President was in failing health. He'd die 8 days after being shot. Then there's President Kennedy. I do not feel that Oswald had anything to do with it. Oswald, an expert marksman in the Marine Corps, had a vantage point where he could have shot Kennedy dead in the forehead before the limo's turned onto Elm. Thn there's Jack Ruby showing up the next day, and walking into the Sheriffs Garage and shooting Oswald. THAT was a cover-up. Ruby assassinated Kennedy and like Oswald said, "I'm a patsy...", he killed Oswald to leave everything covered.