We also used to hear about the ZERO factor, if you were elected in a year ending in zero, you did not survive your first term.
Ronald Reagan showed that "statistics" like these have no bearing on the outcome of future events. George W. Bush is the second president to survive it.
Actually, no. The "twenty year curse" happened as followed...
William Henry Harrison (elected 1840)- Died a month after taking office.
Abraham Lincoln (elected 1860, re-elected 1865)- Assassinated shortly after being inaugurated for his second term.
James Garfield (elected 1880)- Assassinated several months after taking office.
William McKinley (elected 1896, re-elected 1900)- Assaniated in the first year of his second term.
Warren Harding (elected 1920)- Died in 1923.
Franklin Roosevelt (elected 1932, Re-elected 1936, 1940, 1944)- Died in the first year of his fourth term.
John Kennedy (elected 1960)- Assassinated 1963.
Ronald Reagan (elected 1980, Re-elected 1984)- Survived the curse, but was nearly killed by an assassin and had cancer surgery in 1985.
George W. Bush (elected 2000, re-elected 2004) No major health problems.
As you can see, many who were struck by the curse survived their first term.