Early in the campaign, the black commentator Tavis Smiley took a lot of heat when he questioned all the rhetoric, much of it from white liberals, about Obama being “post-racial.” Smiley pointed out that there is “no such thing in America as race transcendence.” He is right of course. America can no sooner disown its racial legacy, starting with the original sin of slavery, than it can disown its flag; it’s built into our DNA. Obama acknowledged as much in his landmark speech on race in Philadelphia in March.

Image Frank Rich Credit... Fred R. Conrad/The New York Times

Yet much has changed for the better since the era of “Guess Who’s Coming to Dinner,” thanks to the epic battles of the civil-rights movement that have made the Obama phenomenon possible. As Mark Harris reminds us in his recent book about late 1960s Hollywood, “Pictures at a Revolution,” it was not until the year of the movie’s release that the Warren Court handed down the Loving decision overturning laws that forbade interracial marriage in 16 states; in the film’s final cut there’s still an outdated line referring to the possibility that the young couple’s nuptials could be illegal (as Obama’s parents’ marriage would have been in, say, Virginia). In that same year of 1967, L.B.J.’s secretary of state, Dean Rusk, offered his resignation when his daughter, a Stanford student, announced her engagement to a black Georgetown grad working at NASA. (Johnson didn’t accept it.)

Obama’s message and genealogy alike embody what has changed in the decades since. When he speaks of red and blue America being seamlessly woven into the United States of America, it is always shorthand for the reconciliation of black and white and brown and yellow America as well. Demographically, that’s where America is heading in the new century, and that will be its destiny no matter who wins the election this year.

Still, the country isn’t there yet, and should Obama be elected, America will not be cleansed of its racial history or conflicts. It will still have a virtually all-white party as one of its two most powerful political organizations. There will still be white liberals who look at Obama and can’t quite figure out what to make of his complex mixture of idealism and hard-knuckled political cunning, of his twin identities of international sojourner and conventional middle-class overachiever.

After some 20 months, we’re all still getting used to Obama and still, for that matter, trying to read his sometimes ambiguous takes on both economic and foreign affairs. What we have learned definitively about him so far  and what may most account for his victory, should he achieve it  is that he had both the brains and the muscle to outsmart, outmaneuver and outlast some of the smartest people in the country, starting with the Clintons. We know that he ran a brilliant campaign that remained sane and kept to its initial plan even when his Republican opponent and his own allies were panicking all around him. We know that that plan was based on the premise that Americans actually are sick of the divisive wedge issues that have defined the past couple of decades, of which race is the most divisive of all.

Obama doesn’t transcend race. He isn’t post-race. He is the latest chapter in the ever-unfurling American racial saga. It is an astonishing chapter. For most Americans, it seems as if Obama first came to dinner only yesterday. Should he win the White House on Tuesday, many will cheer and more than a few will cry as history moves inexorably forward.

But we are a people as practical as we are dreamy. We’ll soon remember that the country is in a deep ditch, and that we turned to the black guy not only because we hoped he would lift us up but because he looked like the strongest leader to dig us out.