David Rice Atchison may or may not have been the 12th president of the United States for a total of one day. At midnight on Saturday, March 3, 1849, outgoing President James Polk’s term expires, but incoming president Zachary Taylor refuses to be sworn in on the Sabbath and puts off the ceremony until Monday, March 5 — which may have meant nobody was president on Sunday, at least officially. Atchison, who was then president pro tempore of the Senate, would have been, under the law at the time, the successor to the presidency. However, he is not sworn in nor does he perform any presidential duties. In later years, when March 4 falls on a Sunday, as it did in 1821,1849, 1877 and 1917, the inaugural ceremonies will be held on March 5.