For 52 years, 14 presidential elections, and 9 presidents, elections occurred keeping or changing the occupant in (the time-before-)the-Oval-Office, from Washington to William Henry Harrison. That all came crashing down on April 4, 1841, one month after Harrison took the oath of office. The Constitution was hardly clear on the matter of succession with words like “the same shall devolve on the Vice President.” Was the vice president a temporary and acting-president until a new election as some saw it? Vice President John Tyler saw it differently and established the precedent of the vice president assuming the duties of the office of president by taking the oath. His Accidency, a nickname given by his opponents, but to every one else he was Mr. President. The longest uninterrupted period for the office of the presidency was from Washington to Harrison, but it would be followed by the shortest period starting with President Tyler.
It would only be 9 years, 2 presidential elections, and 3 presidents until another death took a president. President Zachary Taylor died due to some kind of gastro problem July 9, 1850. Following the precedent established by Tyler, Millard Fillmore took the oath of office becoming the 13th president. The next length of time, Fillmore to Abraham Lincoln, would help establish the average of 22 years between non-election changes in the presidency.
John Wilkes Booth’s bullet would put an end to 15 years and four presidents from Fillmore to Lincoln. The first assassination would be followed by two more. Andrew Johnson would start 16 undisturbed years until three presidents later James Garfield was killed by Charles Guiteau, with Johnson’s acquittal saving him from being the shortest disruption and the first to be removed by impeachment. Chester Arthur all the way through to William McKinley’s assassination by Leon Czolgosz would be 20 years with 5 presidents and just 4 men serving.
The Roosevelt cousins bookend the next two undisturbed periods. Theodore Roosevelt assumed the presidency after McKinley and even won an election in his own right in 1904, something no 19th Century vice president following in Tyler’s footsteps was able to accomplish, also none of them were given an opportunity by a political party to even try, except for Fillmore four years later when the Know-Nothings nominated him to run for the presidency in 1856 coming in 3rd with Electoral College votes. Tyler could have run as an independent in 1844 but reconsidered. So for 22 years and just four presidents, Roosevelt to Warren Harding, the presidency was uninterrupted. Harding’s death ended this run, a mid-point between the Roosevelt cousins. Calvin Coolidge succeeded Harding becoming the 30th president. From Coolidge to Franklin Roosevelt, 22 years would also pass until FDR’s death ended the period with only 3 presidents.
Harry Truman through to John Kennedy would be a period of 18 years, but only 3 presidents with Kennedy’s assassination, the last of a form of death while in office. Lyndon Johnson and Richard Nixon span the next 11 years ending with Nixon’s resignation, the first and only of a president. This was the second shortest period before a disruption and with the next period nicely bookends with the first two periods.
Since Gerald Ford took over the presidency in 1974 as the 38th president the presidency has not been disrupted making the 36 years since 1974 the longest period second only to the Washington to Harrison 9 period. Both the attempted assassination of Ronald Reagan and the impeachment of William Jefferson Clinton could have disrupted the presidency, but thankfully they did not and just 16 years to beat the streak of 1789 to 1841.