On June 5, 1968, Robert F. Kennedy was shot by Sirhan Sirhan shortly after midnight at the Ambassador Hotel, Los Angeles. He was pronounced dead at 1:44 a.m. PDT the following day.

Kennedy was a senator from New York and a candidate in the 1968 Democratic Party presidential primaries. On June 4, 1968, he won the California and South Dakota primary elections. He addressed his campaign supporters in the Ambassador Hotel's Embassy Room ballroom; shortly after leaving the podium and exiting through a kitchen hallway, he was mortally wounded by multiple shots fired by Sirhan. Kennedy died at Good Samaritan Hospital nearly 26 hours later. His body was buried at Arlington National Cemetery near his brother John F. Kennedy's grave.

Sirhan was a Palestinian who held strong anti-Zionist and pro-Palestinian beliefs. In 1969, he testified that he killed Kennedy "with 20 years of malice aforethought"; he was convicted and sentenced to death. Due to the court case People v. Anderson, in 1972, his sentence was commuted to life in prison with a possibility of parole. As of January 2022, his parole request has been denied 16 times.

Kennedy's assassination prompted the Secret Service to protect presidential candidates. Hubert Humphrey became the Democratic nominee but ultimately lost the election to Republican candidate Richard Nixon. Kennedy's assassination has led to several conspiracy theories. No credible evidence has emerged that Sirhan was not the shooter, or that he did not act alone. It has been described as one of four major assassinations in the United States that occurred during the 1960s.

Lyndon Baines Johnson (; August 27, 1908 – January 22, 1973), often referred to by his initials LBJ, was an American educator and politician who served as the 36th president of the United States from 1963 to 1969. He had previously served as the 37th vice president from 1961 to 1963 under President John F. Kennedy. A Democrat from Texas, Johnson also served as a U.S. representative, U.S. senator and the Senate's majority leader. He holds the distinction of being one of the few presidents who served in all elected offices at the federal level.

Born in a farmhouse in Stonewall, Texas, to a local political family, Johnson worked as a high school teacher and a congressional aide before winning election to the U.S. House of Representatives in 1937. He won election to the United States Senate in 1948 after narrowly winning the Democratic Party's nomination. He was appointed to the position of Senate Majority Whip in 1951. He became the Senate Democratic leader in 1953 and majority leader in 1954. In 1960 Johnson ran for the Democratic nomination for president. During the convention he came into conflict with the Democratic front-runner, fellow senator John F. Kennedy. The two men compromised and the Kennedy-Johnson ticket won in the 1960 presidential election. Vice President Johnson would assume the presidency on November 22, 1963, after President Kennedy was assassinated. The following year Johnson was elected to the presidency when he won in a landslide against Arizona Senator Barry Goldwater. Johnson received 61.1% of the popular vote in the 1964 presidential election; this makes his victory the largest share of the popular vote of any candidate since James Monroe's victory in 1820.

Johnson's domestic policy was aimed to create programs that would expand civil rights, public broadcasting, Medicare, Medicaid, aid to education and the arts, urban and rural development, and public services. Johnson coined the term the "Great Society" in 1964 to describe these efforts. In addition, he sought to create better living conditions for low income Americans by spearheading a campaign unofficially called the "War on Poverty"; assisted by a strong economy, the effort helped millions of Americans rise above the poverty line during his administration. Johnson followed his predecessor's actions in bolstering the space program, and it was under his presidency that NASA's efforts became a top national priority and the Apollo Program was expanded. He enacted the Higher Education Act of 1965 which established federally insured student loans. Johnson signed the Immigration and Nationality Act of 1965 which laid the groundwork for U.S. immigration policy today. Johnson's opinion on the issue of civil rights put him at odds with other white, southern Democrats. His civil rights legacy was shaped by signing the Civil Rights Act of 1964, the Voting Rights Act of 1965, and the Civil Rights Act of 1968. During his presidency the American political landscape transformed significantly, as white southerners who were Democratic stalwarts gradually moved to the Republican Party and black voters began moving towards the Democratic Party. Because of his domestic agenda, Johnson's presidency marked the peak of modern liberalism in the United States.Johnson's presidency took place in Cold War America and thus he prioritized halting the expansion of Marxist-Leninist governments. Prior to 1964, the U.S. already had a noticeable presence in Vietnam by providing weapons, training, and aid to South Vietnam in order to stem the communist movement in the region. In 1964, following a naval skirmish, Congress passed the Gulf of Tonkin Resolution, which granted Johnson the power to launch a full military campaign in Southeast Asia, marking the escalation of American involvement in the Vietnam War. The number of American military personnel in Vietnam increased dramatically, and as the war progressed, American casualties soared along with deaths of Vietnamese civilians. In 1968, the Tet Offensive inflamed the anti-war movement and public opinion dramatically turned against the war. Many called an end to U.S. involvement, and opposition to the war surged among draft-age students on university campuses.

At home, Johnson faced further troubles when summer riots began in major cities in 1965 and crime rates soared. His political opponents seized the opportunity and raised demands for "law and order" policies. Johnson began his presidency with near universal support, however his approval declined throughout the decade as the public became frustrated with both the war and domestic unrest. Johnson initially sought to run for re-election, however following a disappointing result in the New Hampshire primary he withdrew his candidacy. The Vietnam War was a major election issue and the 1968 presidential election saw Republican candidate Richard Nixon defeat Johnson's vice president Hubert Humphrey in a landslide. At the end of his presidency in 1969, Johnson returned to his Texas ranch and kept a low profile until he died of a heart attack in 1973.

Johnson is one of the most controversial presidents in American history; public opinion of his legacy has continuously evolved since his death. Historians and scholars rank Johnson in the upper tier because of his domestic policies; his administration passed many major laws that made serious advancements in civil rights, health care, and welfare. However, he is widely condemned for his role in escalating the Vietnam War and the consequences that came along with it, including the deaths of 58,220 American service members, dropping over 7.5 million tons of explosives over Vietnam, and the use of the noxious herbicide Agent Orange.