BOOK REVIEW : A White Man Journeys Through Black America : CROSSINGS: A White Man’s Journey Into Black America by Walt Harrington . HarperCollins $25; 466 pages

Driven by his fears for those closest to his heart, his son and daughter, Walt Harrington set out to listen to the voices of black people in America. The children’s mother, Harrington’s wife of 10 years, is black, and his son and daughter describe themselves as “tan and bright tan.”

When Harrington overhears a racist joke, he realizes suddenly, “This idiot’s talking about my children.” He sees that a racist cop or judge could shape their lives and feels “an urgency for justice that I couldn’t feel as only a white man. . . .”

Harrington is in his early 40s, a prize-winning staff writer for the Washington Post Magazine. He went to a suburban Chicago high school where only one out of the 800 students was black and to a small college in rural Illinois where some black classmates called him a racist.

If anyone along the way asks Harrington, “Why do you care, Whitey?” he has the ace up his sleeve, a picture of his wife and children to prove his stake in the issue.

Trying to find the real voices, Harrington casts his net wide. He talks to a murderer in East St. Louis, a millionaire in Chicago, the only black person in Osceola, Wis., film maker Charles Burnett, black cowboys, a great teacher in Washington, D.C., and Ice-T, Spike Lee and Jesse Jackson. (The encounters with the three celebs are unsatisfying, brief and brusque.)

Harrington is open to casual encounters. On the way to meet a civil rights pioneer, he stops to talk with an old man on the street who admits, “I ain’t got down to eat at Woolworth’s five times.” And he goes on to cast some light on the past in North Carolina: “White people were just against us, and we hadn’t never done nothin’ to ‘em, and I always wondered why they did that, but that’s the way it was.”

“Crossings” is a grand undertaking in the sense of being large as well as noble. The reader will come to feel, on Page 347 or so, that for all his clarity and skill, Harrington could have done more with less.

But Harrington remains a good companion on this trip, in part because he’s wonderfully frank. He gets miffed at black seniors at Little Rock’s Central High School who complain about the problems of being in college prep courses and getting full college scholarships because they’re black. “You’d rather have been in a ramshackle school without books instead of honors classes at Central?” Then to his astonishment they complain about the lazy black folks living off of welfare.

“Crossings” is too long because the author isn’t able to edit his copious interviews. But it is candid and rich. Harrington is at his best in the South, capturing the rich language of men and women over 70 (one interview subject in Natchez is 105).

Harrington’s wife’s family comes from a farm town in southwestern Kentucky; his father-in-law was a master sergeant in the Air Force, and his wife grew up in Europe. Harrington realizes that his marriage probably wouldn’t have worked had his wife been raised in Kentucky or anywhere in America where mistrust of whites is a seemingly obligatory part of black life.

Her father went back to farming; she and her brothers all graduated from college. Her parents’ philosophy, which seems to have worked, is “blacks must act as if they can control their lives, whether or not they can, because otherwise their ambition is sapped and their life consumed by self-pity.”

The question Harrington follows from place to place is “Has life gotten better for American blacks?” Yes, he concludes, the worst indignities are over, especially if you’re a black person with money.

But things are hardly simple. “Only a generation ago, discrimination--legal and social--was all that a person needed to understand most of what was happening between black and white Americans. Race still matters, but it is no longer all that matters.” His advice to his readers is simple but hard: Listen and learn to keep more than one idea in your head at once. Which Harrington has certainly done in this admirable book.