The contest between the Republican candidate Thomas Dewey and Democrat President Truman in 1948 appeared to be a foregone conclusion.
To everyone's surprise, however, Truman won by two million votes.
Lyndon Johnson won a landslide victory in 1964 but faced continuing questions in 1966 because of the war in Vietnam.
Alastair Cooke reflects on the changes in American democracy from the days when everyone knew their place to an age when people were demanding to know what was being done in their name.
Gerald Ford was keen to play down party differences when he announced his intention to stand for the American presidency in 1976.
So what, wondered Alistair Cooke, did it mean to be a Republican or a Democrat? Justin Webb asks whether things are any different today.
Cooke focuses on the dress style of the Clinton camp and wonders what the rejection of the old blue blazer will mean for the American political system.
Cooke saw many presidents come and go, but the election of George W Bush in November 2000 was to be the last.
The veteran broadcaster announced his retirement four years later, by which time America had changed forever.