Growing up in the palest of Chicago suburbs, Senator Hillary Rodham Clinton had some of her earliest exposures to African-Americans through field trips. She sat in the back of her father’s Cadillac as he detoured through the inner city, cautioning her about the fate of people who, in his conservative Republican view, lacked the self-discipline to succeed.

She took a sociology course at Wellesley College that included a trip through Boston’s poor areas. On Tuesdays, she went to a housing project in Cambridge to mentor “underprivileged Negroes,” as she wrote to Don Jones, her minister back home, who had taken her to hear the Rev. Dr. Martin Luther King Jr. speak in Chicago four years earlier.

In a presidential campaign in which race has become a dominant issue, Mrs. Clinton’s early brush with Dr. King has been a recurring theme, invoked as a kind of “a-ha” episode to explain her coming of age on race. Yet Mrs. Clinton’s passage from sheltered Park Ridge, through the ferment of the civil rights era, to competing for black votes across the South, has been more gradual and introspective.