Whenever the office of the vice presidency was vacant, as it was on ten occasions between 1812 and 1889, the office garnered heightened importance, for although he did not assume the vice presidency, the president pro tempore stood next in line for the presidency. Before the ratification of the Twenty-fifth Amendment in 1967, a vacancy in the vice presidency could be filled only by a regular election; several individuals who served during these vacancies were referred to informally as "acting vice president".
Whenever the office of the vice presidency was vacant as it was on ten occasions between 1812 and 1889 the office garnered heightened importance for although he did not assume the vice presidency the president pro tempore stood next in line for the presidency Before the ratification of the Twenty-fifth Amendment in 1967 a vacancy in the vice presidency could be filled only by a regular election; several individuals who served during these vacancies were referred to informally as "acting vice president"