Hi, there! Prior to the passage and ratification of the 25th Amendment to the Constitution (passed by Congress in 1965 with ratification final in 1967), there was no requirement to replace a vacancy in the office of the Vice President, nor was there any legal method in place to actually do it. After John Kennedy’s assassination in 1963 and LBJ’s ascendance to the presidency, there was a concerted effort to change this. The amendment specifically stated how the president could nominate a new VP for approval by Congress (both house and senate). The amendment also added provisions to deal with an incapacitated president, where there was no clear authority to replace the person either permanently or temporarily. In each prior presidential death, the new president went without a Vice President until their term ended. If the office holder ran for re-election (Truman, LBJ, etc.) a new VP was elected. As it turns out, the first time that a new VP was appointed was not due to the death of the occupant, but due to resignation. In 1973, Nixon’s VP Spiro Agnew resigned due to upcoming criminal charges for political actions. Gerald Ford was the first to be appointed rather than elected and became president when Nixon resigned in 1974. Finally, Ford nominated Nelson Rockefeller after Ford became president. One additional interesting point: Since Andrew Johnson had no VP when he became president after Lincoln’s death, had he been removed from office after his impeachment he would have been replaced by the President pro tempore of the Senate, since that was the current order of secession in the 1860s.