Why did the office of the vice president become more important with more responsibilities as the 20th century progressed

The office of the Vice President has become more important with more responsibilities as the 20th century progressed because

The number of Vice-Presidents in the 20th century that became President because of something happened to the President like President John F. Kennedy and his Vice-President Lyndon Johnson; and Richard Nixon and his Vice-President Gerald Ford. With partisan politics strongly dividing Congress, the Vice-President works as the tie-breaking vote in the Senate. Both situations reflect the greater importance of the Vice President´s office (as the President's responsibilities increased in the 20th century, those of the Vice President also increased).

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