If there is a greater American opera than Porgy & Bess, just which would it be?

George Gershwin's magnum opus is riveting theater, peopled by vivid characters. It has some of the greatest tunes ever penned for voices to sing, and some snazzy orchestration.

It also has been controversial since the very start, with people arguing whether it was a real opera or just a musical with overreaching pretensions.

And, in a land ever touchy about racial issues, the idea that three creative white men would characterize a black underclass, complete with a libretto attempting a black dialect, still causes some discomfort.

Gordon Hawkins, who's portraying Porgy in the Dallas Opera revival opening Friday, is reluctant to talk about this aspect of the opera. "Maybe over a few beers, or dinner with some nice wine, we could discuss this," he says. "But not today."

To be sure, Porgy & Bess trades in uncomfortable stereotypes of blacks in poverty as violent and superstitious, prey to alcohol and drugs. What makes the opera further unsettling, perhaps, is that some issues it raises remain all too current in 21st-century America.

"I can understand why people sometimes feel uncomfortable with this," says soprano Indira Mahajan, who is singing the role of Bess. "It's a love story, but it's about an outsider. Porgy has to deal with a physical disadvantage. But we can all relate to that on some level, a feeling that we're outside in some respect.

"And the character of Bess is very layered. She's not just a bad girl gone good and gone bad again. I think a lot of people can identify with her as a woman who's afraid to be alone. She's probably abused on some level, probably also an outsider, and needing to feel safe. When she gets something good, she's unable to trust it completely."

Sensitivity to the characterizations is no anomaly. "It's the same issue that rings true today," Ms. Mahajan says, "with Bill Cosby feeling disgusted with how some programming on television depicts black families.

"I think it depends on how the piece is directed. If we can see the humanity that transcends the issues with these characters, we can all relate to it. It depicts a very real time in American history, and unfortunately it rings true."

Some patrons will always sense a condescending tone in a white men's opera about impoverished blacks, even when – as required by the Gershwin estate – the cast is all black. The Dallas production is also being directed and conducted by blacks, and augmented by performers from Dallas Black Dance Theatre.

But, subtracting our sensitivity to racial issues, Porgy fits right into a century and a quarter of operas set among troubled underclasses, including Carmen, Cavalleria Rusticana, Jenufa, Peter Grimes and even Jake Heggie's Dead Man Walking. In the end, imperfect as they are, the denizens of Catfish Row are portrayed no less sympathetically than Leos Janácek's Moravian villagers in Jenufa.

"The story continues to be so relevant," Ms. Mahajan says, "because these issues aren't going away anytime soon."

Adds Hope Clarke, who's directing the Dallas Porgy: "Just the melodies, Gershwin's thoughts on expressing the people in the community, their ups and their downs – it's so today. It's the only opera that stays today for me, because the problems in Catfish Row we still experience in our lives today, the drugs, the poverty and so on."

In the fall of 1926, the 28-year-old Gershwin picked up the new novel Porgy by DuBose Heyward. A portrayal of life among poor blacks in Heyward's native Charleston, S.C., it even based its male lead on a real-life figure, "Goat Sammy" Smalls, a beggar with damaged legs who went about in a cart drawn by a famously smelly goat. The novel's Catfish Row was based on a tenement (actually called Cabbage Row) across from Heyward's home on Church Street. (The building still stands.)

The book so captivated Gershwin that he immediately dashed off a letter to Heyward proposing they turn it into an opera. Although known primarily as a composer of songs and musicals, Gershwin already had the Rhapsody in Blue and the Piano Concerto in F under his belt, and he was itching to explore the world of opera. Nine years elapsed before the curtain rose on Porgy & Bess, first in a tryout run in Boston, then in a much-cut version at New York's Alvin Theatre.

Heyward (1885-1940) came from an aristocratic family, but the family money was long gone. At age 17 he worked on docks alongside Charleston and barrier-island blacks whose distinctive Gullah culture he would immortalize.

When Gershwin's letter arrived, Heyward's wife, Dorothy, herself a playwright, was already adapting the novel as a play. This, in turn, became the basis of the opera libretto, with poetic arias written by Gershwin's lyricist brother Ira.

Between the demands of Broadway and Hollywood, Gershwin couldn't begin work on Porgy until 1933. He made two trips to Charleston and nearby islands to gain a keener feel for the Gullah language, music and religious customs.

"Yesterday afternoon he and Mr. Heyward went to a Negro church and listened to the singing," the Charleston News and Courier reported at the time. "They plan to arrange to hear as much Negro music as possible and Mr. Gershwin also is anxious to listen in on some of the fish and vegetable hucksters."

In the end, Gershwin quoted no actual songs he heard, but he set his own spin on spirituals, call-and-response idioms, even a minstrel-like banjo song ("Oh, I got plenty o' nuttin' ").

"This is sort of a romanticized version," Mr. Hawkins says, "done by two boys from Brooklyn and a writer from that region. But the music that the prose inspired, that's really a New York thing."

Reviewing Porgy in the November 1935 Modern Music magazine, critic and composer Virgil Thomson wrote: "I don't like fake folklore, nor fidgety accompaniments, nor bittersweet harmony, nor six-part choruses, nor gefiltefish orchestration. I do, however, like being able to listen to a work for three hours and being fascinated at every moment ... I like to think of Gershwin as having presented his astonished public with a real live baby, all warm and dripping and friendly."

Seven decades on, we wouldn't dare describe orchestration with an implied ethnic slur. But we no longer worry much about musical eclecticism and crossover.

Gershwin "was able to capture the gospel, the jazz, the spiritual, the blues," says conductor Wayne Marshall. "It's all in this piece. There's even rap. For me, the most amazing music is the quiet before the storm, this evocative stillness he manages to convey.

"This work for me is timeless. It's a great piece. It is the American opera."