As of 2017, how many U.S. vice presidents have been elected to the presidency while serving as vice president?

There have been four vice presidents elected to the presidency while serving as vice president. They are John Adams, Thomas Jefferson, Martin Van Buren and the most recent, George H. W. Bush.

John Adams served as vice president during George Washington's two terms. During the election of 1796, Adams won by 3 electoral votes over Thomas Jefferson, who in 2nd place became Adams vice president. That was the only election to date in which a president and vice president were elected from opposing tickets. A change in the constitution (12th Amendment) altered the electoral process so the president and vice president would be on the same election ticket.

Thomas Jefferson served as vice president for one term with Adams and was elected president in 1800. He and Aaron Burr received the same number of electoral votes, so the House of Representatives took up the vote and after 36 ballots, elected Jefferson as president and Burr as vice president.

Martin Van Buren won his presidential election by promising to continue Andrew Jackson's policies. The economic problems during the Panic of 1837 helped to sour his chances of re-election.

The latest vice president to be elected president was George H. W. Bush, (41st president, father of George W. Bush, 43rd president) elected in 1988, who served as vice president for two terms during the Reagan Administration.