President-elect Zachary Taylor was set to succeed James K. Polk and be inaugurated as the 13th President of the United States on 4 March 1849. However, March 4 was a Sunday, and Taylor declined to be sworn in on the Sabbath, so his inauguration was deferred for a day. Now, over one hundred and fifty years later, a ubiquitous bit of presidential apocrypha is the claim that someone else served as President during the twenty-four hour period between the expiration of Polk's term and the swearing-in of Taylor. A plethora of trivia reference sources state that Missouri senator David Rice Atchison was (or acted as) President for that one day, but claims placing him in that office are really nothing more than latter day "what if?" fantasies based on erroneous assumptions and interpretations.
The office of President was established by the ratification of the Constitution of the United States of America in 1788, Article II, Section 1 of the Constitution.