In 1849, inauguration day, March 4th, happened to be a Sunday. James Polk’s term ended at noon that Sunday, but President-elect Zachary Taylor refused to be sworn in on the Sabbath.
So who was President? Some have claimed it was Missouri senator David Rice Atchison. Atchison was President Pro-Tempore of the Senate and, as such, third in line to the presidency. Atchison must have been president for a day.
In 1821, 1877 and 1917 the inauguration was also changed because of Sunday. James Monroe’s second inauguration was on March 5, 1821. Rutherford B. Hayes took the oath of office privately on March 3. Woodrow Wilson was inaugurated for his second term on March 5.