Gwen Ifill began her journalism career at the Boston Herald in 1977, covering race riots by telephone. It was too risky for a young black reporter to venture onto the grounds of South Boston High School. Thirty years later, a black man announced his candidacy for president of the United States. Obama is the leading edge of a sea change in American politics, but his is by no means the only story. Ifill offers incisive, detailed profiles of other prominent...