But in death Richard Nixon and Jacqueline Kennedy Onassis forged a curious bond. Not because they died within a month of each other, after receiving their last treatment at the same hospital - but because of the way they chose to die, maintaining control of the last act of their lives, and with it their dignity as human beings. It may prove their most important legacy.
The US is the place that pretends death doesn't happen, whose every instinct is to treat it as a disease - with no cure yet, but who knows? Thus the euphemisms. Television announcers speak of 'fatalities' rather than people being killed in an accident. Every instrument of medical wizardry is used to prolong lives even by days, even if the condition is terminal.
But not in the cases of Nixon and Onassis. The 37th President died four days after suffering a stroke, in accordance with his instructions that nothing extraordinary should be done to keep him alive if he was mentally incapacitated. Jackie Onassis took a similiar course once her doctors had said her cancer was inoperable.
In February, when she started treatment for lymphoma, she had taken out a 'living will' setting out how she wanted to die. Her desire was to return home, and she did so. A day later she died peacefully in her own bed, surrounded by her family and friends.
Living wills are nothing new. Back in 1976 California allowed people to put in writing their wish not to have their life extended by artificial means if they were terminally ill, and protected physicians who followed those instructions from the threat of criminal charges. Today every state except New York and Missouri has such laws. Since 1991 hospitals have been required to tell patients of their rights and to provide legal forms upon request. Even Bill and Hillary Clinton have publicly announced they are drawing up living wills. Nevertheless, only one in five adult Americans has done so - or signed a 'health proxy' granting a close relative power of attorney to decide how far medical treatment should go. Thanks to Richard Nixon and Jacqueline Onassis, that may be changing.
Death has moved from taboo to topic of the moment. Choice in Dying, a New York organisation that promotes living wills, reported that daily inquiries rose to 500 from around 100 after Nixon died. After the extraordinary national outpouring for Onassis, the figure quadrupled again, to 2,000 a day.
A book by Yale University medical historian Sherwin Nuland, How We Die, which explains in clinical terms precisely that, is a national best seller. A small revolution in attitudes is under way. Death is being accepted as the end of nature's cycle - and people are remembering, in Dr Nuland's words, 'that the chief actor is the dying person, not the doctors trying to save him'.
Of course, in this land where religion, ethics and law (not to mention money) can turn straightforward moral choices into knots of Gordian complexity, it is not always so simple. Take the wretched tale of Joey Fiori of Philadelphia, reported this week in the New York Times. His brain was severely damaged by a motorcycle accident in 1971. Since 1976 he has been in a vegetative state after a treatment error that left him unable to think, feel, see, hear, move or swallow. Mr Fiori is fed by intravenous tube. At 44, he could 'survive' for decades, at a cost of dollars 150,000 ( pounds 100,000) a year. His mother wants him disconnected, so he can die peacefully. But she has been told this is impossible, short of 'clear and convincing evidence' her son left such instructions. Every night, she says 'I pray that God will take him'.
Economic and demographic pressures have a momentum of their own. Controlling health care spending, the vast bulk of which goes on the elderly, is the biggest long-term challenge facing the American government. As the babyboomer generation ages, the number of people over 65 is projected to double over the next 20 years; someone has to pay the cost of looking after them. By their examples, Nixon and Onassis may make that burden a fraction lighter.