Only three mothers of presidents lived longer than their sons, one of whom was Jane Knox Polk. She died on January 11, 1852, more than three years after James Knox Polk, 11th president of the United States. The only other presidential mothers to outlive their sons were Eliza Garfield and Rose Kennedy, both of whom lost their boys to assassins.
A combination of overwork and cholera seems to have done in President Polk. At 53, he died relatively young -- younger, in fact, that any other president who died of natural causes, and third youngest among all the presidents, living longer than James Garfield (49) and John Kennedy (46). Polk survived his term by a little more than three months.
According to the web site of the President James K. Polk State Historic Site in North Carolina: "The oldest of ten, Polk was raised on tales of the American Revolution by his father, a prosperous farmer. A pious Presbyterian, Polk's mother was said to be descended from the fiery Scottish religious reformer John Knox. Both parents instilled in their son a fierce patriotism, a keen interest in politics, and a deep religious faith."