Final answer:
Eight vice presidents have had to succeed a president because of death, with one extra case due to resignation, making a total of nine. The 25th Amendment to the U.S. Constitution clarifies the process of succession, which has been invoked when vice presidents have ascended to the presidency. This reflects the evolving role and potential influence of the vice president within the government.
Step-by-step explanation:
Presidential Succession and the Vice Presidency
In the history of the United States, vice presidents have been called upon to succeed the president on multiple occasions. This succession most commonly occurs due to the death of a sitting president, which has happened eight times. Four of these were assassinations, and one instance was due to resignation, which was when Gerald Ford succeeded Richard Nixon after his resignation amidst the Watergate scandal. Unlike the two instances where vice presidents were elected to the presidency following their term as vice president (Martin Van Buren in 1837 and George Bush in 1989), Ford remains the only individual to have become president without first being elected as either vice president or president.
The 25th Amendment, ratified in 1967, clarifies the process of presidential succession. If the presidency is vacated, the vice president assumes the role of president and nominates a new vice president who must be confirmed by both the House and the Senate. This ensures the continuity of government, as exemplified by the succession of Lyndon B. Johnson following the assassination of President Kennedy. The amendment also outlines the line of succession should both the president and vice president be incapacitated at the same time, starting with the Speaker of the House.
The vice presidency has evolved over time, transitioning from a role with few official responsibilities to a position that can involve significant influence and partnership in governance, depending on the current president’s appraisement of the vice president's role.