From the corn fields of Iowa to the White House - candidates from Jimmy Carter to Barack Obama have taken a grassroots path to the Presidency. But how did the long, colourful contest for the most powerful political office on earth get to be this way? Journalist and American politics expert John Barron follows the story back to the anti-war movement of the 1960's and along the way meets some of the men and women who paved the way for the election of...