John F. Kennedy (1963)

The assassination of President John F. Kennedy on 22 November 1963 remains the most analyzed event in American history, with the Warren Commission's finding of a lone gunman disputed by 60% of Americans as of 2023. The 25th Amendment, clarifying presidential succession, was also ratified in 1967 as a direct result. The assassination reshaped the Secret Service's protective protocols, which now cost over $3 billion annually.