Ida Mae Brandon Gladney lived into her 90s and died six years ago. Hardly anybody outside the rural Mississippi village of her birth and the Chicago South Side neighborhood where she resettled knew her name. That is about to change, because her life is told in intimate detail in a new book destined to educate readers for a long, long time.

During a 50-year stretch of the 20th century, African-Americans left Southern states by the millions to settle in places such as Chicago and New York. Leaving their familiar homes obviously constituted a wrenching experience for the women and men, many of whom had never traveled even as far as the next county, lacked money, had been kept down by enforced slavery and survived murderous threats, including the specter of being lynched by white Southern vigilantes.

As black author Richard Wright said in a poem that provided the title to Isabel Wilkerson's new book, he wanted to "bend in strange winds/respond to the warmth of other suns. ... "

Academics have documented portions of the migration, although some of the research is colored by overt bigotry. A few skilled journalists have published books, too, most notably Nicholas Lemann in "The Promised Land." Wilkerson might have topped them all in breadth, depth and readability, as she builds her narrative around three migrants, relating their experiences as much as is practical through their own perceptions.

Robert Foster left Monroe, La., for Los Angeles. George Swanson Starling left Eustis, Fla., for New York City. Ida Mae Brandon Gladney left Okolona, Miss., for Chicago. Wilkerson chose them not only for geographical reasons, but also because each "represented some aspect of the emigrant psyche, of the patterns of adjustment facing anyone who has ever left one place for another, desperate to make a go of it."

Wilkerson, a Pulitzer Prize-winning journalist, spent years locating migrants and their descendants. She held conversations with Gladney, Starling and Foster during their twilight years.

Shattering stereotypes, she becomes a wonderful teacher.

She grapples with overly broad assertions that many migrants left the South because they feared being lynched or because cotton production had become mechanized.

"The mechanical cotton picker did not exist when the exodus began," she writes. "The migration had been underway for some 30 years before the first viable prototypes were actually in use in the fields."

For the most part, she writes, migrants left the South in search of improved material and cultural lives. "It was not one thing, some weighing more heavily in one migrant's heart than another but all very likely figuring into the calculus of departure."

Wilkerson contradicts the conventional wisdom that the migrants destroyed the fabric of Eastern, Northern and Western metropolises through out-of-wedlock births, welfare dependency and illiteracy.

"Perhaps it is not a question of whether the migrants brought good or ill to the cities they fled to ... but a question of how they summoned the courage to leave [the South] in the first place, or how they found the will to press beyond the forces against them and the faith in a country that had rejected them for so long," she writes. "By their actions, they did not dream the American Dream, they willed it into being by a definition of their own choosing."

Steve Weinberg is the author of "Taking on the Trust: The Epic Battle of Ida Tarbell and John D. Rockefeller." He is at www.steveweinbergwriter.com.