“Between 1840 and 1960, US presidents who were elected in years ending in ’0′ were either assassinated or have died of natural causes while in office. This 20 year death cycle had been appreciated for many decades. An edition of Ripley’s Believe It or Not, published in 1934, noted the coincidental 20 year pattern of presidential deaths between 1840 and 1920, with question marks inserted for the upcoming 1940 entry. This implied that there could be a continuation of the cyclic pattern, which was fulfilled when Franklin Roosevelt was re-elected in 1940 and subsequently died in office in 1945. Based on this 20 year death cycle, several astrologers correctly predicted the death of President John F Kennedy when he was elected in 1960. Similarly, it was expected that President Reagan would also die in office, which almost came to pass with the attempted assassination on March 30, 1981. This marked the end of the 20 death cycle, as President George W Bush completed his full term in office.

Strangely, two Presidents, who were elected in years ending in ‘0’ — Abraham Lincoln and Franklin D Roosevelt — both died in their following term after being re-elected in the ‘4’ ended year. Therefore, the 20 year death cycle anticipated the successful re-election of these presidents to the oval office.

Using the Fisher Exact Probability test, the presidential death cycle was shown to yield a significance level of 0.00004, thus confirming that the cycle was very unlikely to occur by chance. A mathematician, Michael Capobianco, applied a more conservative methodology and still produced significance at p < .01.

The 20 year death cycle appears to be more than just coincidence, especially as only one president between 1840 and 1960 died in office and was not elected in a '0' year. The exception was Zachary Taylor, who became president in 1848 and died of a stomach ailment in 1850. The cause of death was suspicious and it was speculated he had been poisoned with arsenic. In 1991, his body was exhumed to investigate this theory, but the findings proved negative."