In 10 plays, each situated in a different decade of the 20th century, August Wilson has explored the comedy and tragedy, thwarted passions and visionary aspirations of African-American history and culture.

All but one of the plays are set in Pittsburgh's Hill District, which becomes a crossroads and microcosm of that epic story. Only "Ma Rainey's Black Bottom," the first play to reach Broadway, is set elsewhere, in a Chicago recording studio, because Mr. Wilson said he hadn't yet realized that the Hill could so completely epitomize black America.

Along the way, Mr. Wilson's American epic looks back to slavery and forward to a full equality that glimmers in the distance. And it looks backward further to the fearsome middle passage of the slave ships and the mid-Atlantic City of Bones, prophetic and apocalyptic testimony to the human cost of slavery and the spiritual burden and inspiration passed to its descendants.

The cycle deals also with the waves of fresh black migration from the agrarian South to the industrial North. A recurring theme is the people's destiny and each individual's "song" -- the sense of personal spiritual relationship to that history. Being in tune with that song can turn the future, as Mr. Wilson once described how theater inspired his own life, into "a road which has welcomed me with fresh endearments and sprouted yams and bolls of cotton at my footfall."

In most of the plays there are characters who embody that legacy of past suffering and hard-won wisdom. Chief among these is the semi-mythical Aunt Ester, a shaman and healer, supposedly born in 1619, the year the first slave ships arrived with their shameful cargo in Virginia -- although we eventually realize that hers is a hereditary function, passed down from generation to generation.

Ester appears in the flesh only in "Gem of the Ocean," set in 1904, when her house at 1839 Wylie Avenue is a sanctuary for veterans of the old underground railway and a command post for opposition to the new slavery of company store, kickbacks to employers and racist unions.

We next hear of Ester in "Two Trains Running," set in 1969, where she offers off-stage hope to one of Mr. Wilson's young men seeking a viable future, and she dies in "King Hedley II" (1985). But her spirit is still alive in "Radio Golf" (1997), when an urban redevelopment scheme may dishonor the history embodied in her house.

Although the nine plays that have so far reached New York have been laden with laurels by critics, they have found their true home not in the commercial milieu of Broadway but in professional theaters all over America. There, in spite of rich connective themes and a couple of recurring characters, including the Hill itself, their triumphant effect makes it clear that they stand alone as individual achievements. Rich in both humor and pain, powered by lively, expressive language and poignant story, they have become classics of the American stage.

For scope and power, the Pittsburgh Cycle is a coherent, focused achievement unmatched by any other American playwright.

In the following summaries, the first date is when the play takes place; the second, when its finished version reached New York:

"Gem of the Ocean," 1904 (2004)

Into Aunt Ester's house comes a young man, Citizen Barlow, seeking to have his soul washed of guilt. He's welcomed by elderly veterans of the underground railway; menaced by Caesar, a black man who serves the white mill owners as a latter-day overseer; and intrigued by Black Mary, Ester's apprentice healer. The torch of resistance is passed.

"Joe Turner's Come and Gone," 1911 (1988)

Seth and Bertha Holly's boarding house is a temporary haven for people on the move northward to find a new life or in search of family members lost under the oppression of sharecropping and chain gangs. Bynum, the shaman, speaks of the "binding song" which can put them in touch with their destinies, and presides over a celebratory "juba" that unleashes Herald Loomis' terrifying vision of the City of Bones.

"Ma Rainey's Black Bottom," 1927 (1984)

While the white agent and studio boss wait angrily for blues star Ma Rainey to show up for her recording date, the four black musicians in her band rehearse and bicker, tell stories and dream. Tensions rise, especially for Levee, the hopeful trumpet player played magnetically by Charles Dutton on Broadway. In this first Wilson play to reach New York, both the playwright and his first angry young man issue their challenge to America,

"The Piano Lesson," 1936 (1990)

The most precious possession of the Charles family is an upright piano. When they were slaves, in 1856, a Charles child was traded for it and the child's father carved his grief on it in scenes of family history. Years later, his descendants reclaimed the piano. Lives were lost. Now it is the focal point in a struggle between their descendants, brother and sister Boy Willie and Berniece, over how to use this painful legacy. She wants to keep its legacy intact and untouched, but he wants to sell it to buy the land on which the family had been slaves. Other family members get involved in the dispute, and then the angry ghost of the last Sutter arrives to have its say.

"Seven Guitars," 1948 (1996)

Floyd Barton is a natural musician with one hot song who, in the expansive atmosphere after World War II, dreams of the big time. But as the play begins, his wife and friends mourn his death. In his only play constructed in flashback, Mr. Wilson takes us back to explore what happened. Who killed Floyd Barton, but more important, why, and at the junction of what issues and emotions?

"Fences," 1957-58 and 1963 (1987)

The most popular play of the cycle, a money-maker on Broadway with towering performances by James Earl Jones and Mary Alice, "Fences" is often compared favorably with "Death of a Salesman." Troy Maxson was a Negro League baseball star who spent many years in jail; now he's a trash collector fighting for blacks to be allowed to drive as well as haul. Opposing him is his teenage son, hopeful of something better, while his wife, older son, brother and friend bear complex testimony.

"Two Trains Running," 1969 (1992)

In the aftermath of the riots following the assassination of Martin Luther King and in the heyday of black power, a bumptious young man named Stirling arrives at Memphis' diner to learn his way around the Hill and check out Risa, a pretty waitress who has scarred herself in protest against sexist men. The deranged Hambone seeks the ham he was promised, refusing to settle for a chicken. Is that a model for Memphis in his dispute with the city over his land? The resident philosopher is Holloway, but there's also Aunt Ester, whom Stirling hopes to see. Surprisingly, his '60s play is Mr. Wilson's least angry and most compassionate, perhaps because he originally thought to set it in the '40s.

"Jitney," 1977 (original, 1982; rewritten, 2000)

Out of a scruffy jitney station in the Hill, Becker and four other men hustle to make a living driving places other cabs won't go. In between calls, they gossip and bicker with each other and the neighborhood numbers runner. Then Becker's son arrives, freed from a long jail term for a murder of passionate principle, and the central conflict is joined. But it's the by-play among the men that makes this such an audience-friendly play.

"King Hedley II," 1985 (2001)

The quasi-Shakespearean title is justified: Hedley, who was named King by his father, the strange West Indian in "Seven Guitars," is indeed a tragic figure of great stature. In this darkest Wilson play, Hedley struggles to earn respect and carve out a life in a dusty Hill backyard, but his plans go awry and his family heritage, in the figure of Elmore, his mother's one-time lover, rises up to doom him in the end.

"Radio Golf," 1997 (2005)

In Mr. Wilson's first play set among the black bourgeoisie, Harmond Wilks is running for mayor and planning a bold redevelopment deal, urged on by his materialistic wife and friend. At particular issue is 1839 Wylie, the old house that was once Aunt Ester's. That historical connection has been lost, but there are other voices urging Harmond to reconnect with his people and their deeper values.