As we saw last week, nine times in U.S. history a vice president has succeeded to the office of president of the United States because the previous holder of that office died or resigned.

Five of those presidential successions occurred in the first year of a presidential term. Consequently, the new presidents served three-plus years in office with no vice president since that office remained vacant.

Of these five deceased presidents, two died in the first year of their first term (William Henry Harrison and James A. Garfield) to be succeeded by, respectively, John Tyler and Chester Alan Arthur...