Who was the president with the shortest term of office?

William Henry Harrison Harrison served as president for 32 days. Though technically David Rice Atchison was president for a day. The Constitution says, in the absence of a president or Vice-president, the congress can name a substitute. James Polk ended his term on March 4, 1849 and his successor, Zachary Taylor, did not take the oath until March 5. The vice- president had resigned as president of the senate the previous Friday 3 March and Aitchison was elected by the senate to take his place pro tempore. As president of the senate throughout the weekend he was therefore the legal president until Taylor was sworn in.