Notes
Longest/shortest speakership
The longest speakership contests on record, lasting from December 3, 1855, to February 2, 1856, was for Nathaniel Banks. He was chosen on the 133rd ballot, receiving 103 votes out of 214 cast, or five less than an absolute majority.
Theodore M. Pomeroy served as the 26th speaker of the United States House of Representatives for one day, from March 3, 1869, to March 4, 1869. He decided to retire from politics on the second day.
Filibuser-proof majority
The Republicans have never held a filibuster-proof majority in the Senate. The Democrats have had such a majority in these 20 years: 1941, 1942, 1959-68, 1970, 1975-78, 2001, and 2009-10.
25th Amendment
Before the ratification of the 25th Amendment to the Constitution on February 10, 1967, vice presidents who either died in office or had to assume the presidency could not be replaced. You'll see gaps (white space) in the chart where this has occurred. When Spiro Agnew resigned on October 10, 1973, the 25th Amendment allowed Nelson Rockfeller to become Gerald Ford's vice president.
Deadly streak
The years from 1933 to 1940 were deadly for House speakers. Speaker Henry Rainey died on August 19, 1934. He was replaced by Speaker Jo Byrnes who died on June 4, 1936. Speaker Byrnes was replaced by William Bankhead who stayed alive until September 15, 1940.The streak was broken by Speaker Sam Rayburn who stayed alive for the duration of his speakership.