July 4, 1826: explaining the same-day deaths of John Adams and Thomas Jefferson

John Adams and Thomas Jefferson died on the same day, July 4, 1826. Both were old men--Adams was 90, and Jefferson was 83--and both were ill, though Adams had been in comparatively robust health until just a few months earlier and Jefferson had been ill for an extended period. They had been rivals, indeed enemies, for some time; Jefferson had defeated Adams in the presidential election of 1800. But they had repaired their differences and had pursued an active correspondence with each other in the years before their deaths. On that final day, the 50th anniversary of the signing of the Declaration of Independence, Adams died at his home in Quincy, Massachusetts, and Jefferson died at his home in Monticello, Virginia, the two separated by hundreds of miles and by many days of overland travel time.