The assassination of President John F. Kennedy during a trip to Dallas in 1963 left a nation in mourning and America's royal family torn apart.

"We're very focused on family because it's the only thing that got us through," former Rhode Island Rep. Patrick Kennedy, the son of Ted Kennedy, who was born four years after the tragedy, told ABC's Byron Pitts in an interview for "This Week." "It certainly got my dad through."

After JFK's brother, Robert, was also assassinated in 1968, it was left to Ted Kennedy, the youngest of the brothers, to hold the family together.

"My father, frankly, was not just my father," Patrick Kennedy said. "He was the father for my cousins, John and Caroline. And all my Robert Kennedy cousins too."

Less than an hour after the Kennedys' plane touched down JFK was shot, allegedly by Lee Harvey Oswald. The horrifying events of that day still burn brightly in the minds of the men and women who were there.

"I saw Jackie. Pink hat and pink coat," said Tina Towner, who shot footage of the presidential motorcade from outside the Texas School Book Depository when she was only 13 years old. "I heard three gunshots."

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Dan Rather, anchor of AXS-TV's "Dan Rather Reports," covered the trip for CBS News. He remembers a sense of foreboding before the president and Mrs. Kennedy traveled to Texas.

"Everybody knew if there was going to be trouble anywhere it would be in Dallas," he said. "It's very important to understand, when I say 'Well, there's going to be trouble in Dallas,' no one I knew of was thinking assassination."

Dr. Ronald Jones was paged to Parkland Hospital Emergency Room with a message that the president had been shot.

"There was no sign of life in my opinion," Jones said. "He had a fixed stare. His eyes were open. I never saw him move. I never saw him breathe."

Fifty years after that tragic day, JFK's legacy still lives on - not in spite of his untimely death, but because of it.

"He represents the best in us because it was cut short," award-winning documentary filmmaker Ken Burns told Martha Raddatz today on "This Week."

JFK's three-year presidency was an "evanescent moment," Burns said. "It's fleeting and it just stays there for a couple of seconds and we wish we could extend it."

Although it is unclear what JFK might have accomplished had he lived, it is "the hope and the ambition and the sense of possibility" that his death left in the hearts of Americans that elevates him, Burns said.

"We invest that legacy with all of our hopes and all of our wishes," he said.

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