When I first heard that Morgan Freeman was going to play Nelson Mandela in a film directed by Clint Eastwood (Invictus), I was not surprised. Indeed, it's the rule rather than the exception that a black-American actor of his stature should tackle the role of a black South African. In the way British actors must play a Southerner (Kenneth Branagh in The Gingerbread Man, Cate Blanchett in The Gift—yes, Blanchett is Australian, but let's overlook that), black-American actors must, to cap their careers, play a black South African. This has been the tradition for over half a century.

But why is this the case? Why have so many black-American actors played black South Africans, instead of, say, playing black Zimbabweans or black Kenyans? The answer is simple. The history of South Africa, and its institutionalized racial oppression (apartheid), speaks directly to the black experience in this country. The humiliation, the suffering, and the unrelenting force of white–South African exploitation fit perfectly with the humiliation, the suffering, and the unrelenting force of white exploitation in America. For a black American to play a black South African, all that's needed is a change of accent; the rest—the sorrow, the anger, the hurt, the hope—comes naturally.

It all begins with Cry, the Beloved Country (1952), a movie based on a novel of the same name. In this movie, two great black- American actors meet, Canada Lee and Sidney Poitier. For the former, it is the end of a short but brilliant career; for the latter, it is the start of a long and brilliant career. Poitier brings to his character, a handsome reverend, the kind of hope that can be found in an actor who has the future ahead of him; in Lee, who convincingly (maybe too convincingly) plays a destitute black South African, we see the kind of despair that's expected from a black-American actor who has been persecuted by the Hollywood machine. There is one scene that shows Lee walking down a dusty road, his look, his body, his cracked lips—it's just too sad to believe. (Agreed, Poitier spent his childhood in the Bahamas, but let's overlook that. His career was not established there, and the roles that made him famous were black-American roles.)

In Cry Freedom (1987), Denzel Washington, one of the most famous black-American actors of the '80s and '90s, plays Steve Biko, a black–South African activist who was killed while in police custody. To be honest, the film is really about a liberal newspaper editor, played by Kevin Kline, who attempts to expose the truth about Biko's death. Nevertheless, Washington brings emotional weight and intelligence to his character. I must also admit that when I watched this movie in 1987, it totally ruined my date. The young woman who accompanied me was moved to tears by the murder of Biko. She cried in the theater, she cried in the lobby, and she cried in the car. I could not make out with her.

The musical Sarafina! (1992) was Whoopi Goldberg's vehicle for a black–South African role. In the movie, she plays an inspirational teacher, Mary Masembuko, who has bright and colorful students. The movie is not very good, but it does have an actual black South African playing a black South African (none other than Miriam Makeba—she died last year on an Italian stage, right after performing her most popular song, "Pata Pata").

Danny Glover has the distinction of playing a black South African not once but twice. (To be honest, he plays a colored—or mixed-race—South African in Boesman & Lena [2000], but for the sake of convenience, let's overlook that.) In Bopha! (1993), not only does Glover play a South African, but Alfre Woodard does as well—Glover is a black cop and Woodard is his wife. The film, sadly, is not very good. Nor, for that matter, is Boesman & Lena, which also has another famous black American playing a black South African: the eternally beautiful Angela Bassett (yes, yes, she actually plays a colored South African and not a black South African, but, again, for the sake of convenience, let's overlook that).

Then there is Dangerous Ground (1997), which contains the strangest of all performances in the tradition of black Americans playing black South Africans: Ice Cube as Vusi Madlazi. There is, however, an important twist: Madlazi grew up in L.A., and the movie is about his return to post-apartheid South Africa. This curious feature of the story freed Cube from learning what all the other black Americans have to learn: an African accent—instead, he speaks and acts like someone who, like him, is from the rough streets of L.A. Another strange thing about this film is Elizabeth Hurley, who plays a white–South African prostitute. She and Cube join forces and save the day in post-apartheid South Africa.

But, in general, the reason so many black Americans play black South Africans is because it's another way of telling their story, their American story. Freeman (in Invictus) is not the first famous black American to play Mandela. That honor goes to Poitier, who played the first black president of South Africa in the 1997 TV series Mandela and de Klerk. Freeman, however, has the distinction of not only doing a great Mandela but also a great South African accent. The movie is set in 1995, during the days leading up to the Rugby World Cup in Cape Town. Mandela uses the sport, which once separated his country, to unite it. Freeman absolutely loves being in his character. It's easy to imagine him playing Mandela for the rest of his life. But what is the movie really about? Not South Africa or Mandela, but America and Obama. Eastwood, the director, is speaking to his fellow Americans. His message? The situation in South Africa in the mid-'90s is somewhat like the situation here at the end of the '00s. Big changes are happening, but we must still love our country and our president.