After the speeches and the debates and polls within the margin of error, after the town halls and the caucus nights and millions of dollars in 30-second ads, after the New Hampshire tears and Rev. Wright and the Palin effect, Americans finally get to vote.

Ordinary people, by the millions, either because they are inspired, angry, excited or distressed will decide who gets to be called the most powerful man in the world. The fact that a black man of extremely modest origins and limited political experience may emerge as the winner only makes the whole experience even more mind-boggling.

The fact that his grandmother, the woman who helped raise him and who he credits with helping mold him, did not live to see it, makes it even more heart-breaking.

If the polls turn out to be completely unreliable and Barack Obama loses to John McCain today, it will set off a heated debate about race in America. But even if that happens, this will already be a different America from the one that allowed Obama, on a cold day in February 2007, to stand on the steps of the Old State House in Springfield, Ill. and more than implicitly compare himself to Abraham Lincoln. Change, which Obama would talk about relentlessly for a year, was not possible in a divided country, he said.

"By ourselves, this change will not happen. Divided, we are bound to fail," he said, referring to Lincoln's famous "A House Divided" speech. "But the life of a tall, gangly, self-made Springfield lawyer tells us that a different future is possible."

That 2007 speech captured all the possibility of America, as well as the political realities of the day. It acknowledged Obama as the longest of long shots.

"I recognize there is a certain presumptuousness—a certain audacity—to this announcement. I know I haven't spent a lot of time learning the ways of Washington. But I've been there long enough to know that the ways of Washington must change," he said.

But the misplaced presumptions were not simply ones of personal ambitions and political daring; they were a rejection of deep historical and cultural truths that a black man could not be elected president of the United States.

And whatever the outcome from these past 21 months, whatever we thought of the country back on that cold day in February, we all feel something a bit different today.

It is hard to make a case or present a scenario for how John McCain could win the election, except that he has shown, merely by his perch atop the Republican ticket, that he does have some internal instinct for survival.

As the returns come in tonight, McCain is likely to lose Pennsylvania, his must-win state, followed by Virginia and Colorado. If that happens, he will join a long list of men famous in the day, who are barely remembered for having come so close.

An Obama win will set off celebrations in black households, not just across the country but across the globe. It was only 150 years ago that Lincoln delivered his "House Divided" speech, and the year before that the Supreme Court, in the Dred Scott decision, decreed that blacks could not be citizens of the United States. Just 61 years ago a black man got to play major league baseball for the first time. And if Obama is elected, he will leave the U.S. Senate without a single black member.

But the potency of the moment will travel far beyond the precincts of blackness. One of the truest things that Barack Obama has said in this campaign is that his story would only be possible in America; to whatever the extent his story is about race, his success has been a repudiation of an ugly past and some absolution for our long and sinful racial history. That is an American story. And this is a different America.

Go vote.

Terrence Samuel is deputy editor for The Root.