William R. de Vane King
The U.S. has had 46 Vice-Presidents since the U.S. Constitution went into effect. During that same time we have had 42 U.S. Presidents. The office of Vice-President has become vacate several times, either due to the death or resignation of the Vice-President or the President. Eight U.S Presidents have died while in office, one has resigned (Richard Nixon), leading to then current Vice-President being sworn into office as the new President.
Only fourteen Vice-Presidents have gone on to become President. With nine of those Vice-Presidents assuming the office through constitutional succession, those are not great odds. Two of those Vice-Presidents, Andrew Johnson and Richard Nixon, were openly vilified and faced disgrace. I'm not an presidential historian, but looking over the list I would say that a majority of the remaining twelve had successful Presidential administrations.
The 46 U.S. Vice-Presidents who have served this country are, for the most part, unknown names and quantities to anyone other than professional historians. Most Americans can name at least some of our recent Vice-Presidents. Of the fourteen Vice-Presidents who became President, many of them are quite well-known. I'm familiar with the names Aaron Burr, George Clinton of New York, J.C. Calhoun and some others who achieved their own fame. But I'm afraid many of the others are just names on a page to me. (For instance, I never heard of William R. de Vane of Alabama, who died of tuberculosis after only 45 days in office. But maybe that's only me).
In the modern era, a candidate for President looks for a running-mate who can "balance" the ticket and increase the chances for winning in November. John F. Kennedy's choice of Lyndon B. Johnson was important in winning the 1960 election. Quite often the choice has made little or no difference. It remains to be seen how important the two Presidential candidates choice for Vice-President will be in the election of 2008.