The longest, most demographically-difficult and highest-turnout campaign ever for the presidential nomination of an American political party was settled Tuesday night when Barack Obama — the son of an African immigrant and a daughter of rural Kansas — secured sufficient delegate support to assure that he will be selected as the Democratic nominee for president of the United States.

It was a historic moment for Obama, for the Democratic party and for the American experiment.

For the first time since the founding of the republic, a major party has nominated an African-American man for the presidency.

There is drama in that – as there will be drama in Obama’s acceptance of that nomination on the 45th anniversary to the day of the Rev. Martin Luther King Jr’s “I Have a Dream” speech.

But there is drama, as well, in the fact that this African-American man has prevailed in a close contest with — not against, but with — a woman. Hillary Clinton.

Much has been made of the race and gender divisions that were highlighted during a robust if sometimes unsettling primary fight. But who really expected that the first campaign in which America would seriously consider the prospect of making a person of color or a woman president would be easy?

Instead of focusing merely on these divisions, it is important, also, to consider the most remarkable fact of this race: That in a country where women and most African Americans were denied the right to vote in 1908, a woman and an African-American man split the highest-ever turnout in a presidential nomination contest in 2008.

Hillary Clinton’s mother was born before women had the right to vote.

Barack Obama’s father came to the United States as a foreign student at a moment in history where many American states still denied the franchise to those whose skin was not white.

Their children have competed, seriously, for the most powerful position in the country.

Obama and Clinton each secured something in the range of 18 million votes over the course of the five-month process that began in Iowa and finished Tuesday night in South Dakota and Montana.

The two candidates and their supporters will argue for a little longer about who won the most popular votes and where and how to count them.

But the reality is that more than 36 million Americans participated in the caucuses and primaries of a major political party and that has, since January, been in the process of breaking down barriers that were erected more than 200 years ago by inspired but imperfect founders. For most of its history, America has been an incomplete democracy. But, for the past five months, it has struggled to deliver on the promise of a more perfect union.

That struggle is not finished.

Barack Obama and Hillary Clinton still must reconcile their ambitions and their options. Obama is right when he says, “I will be the Democratic nominee for President of the United States.” But Clinton must help her fellow senator dot the “i” and cross the “t” in the word candidate.

Along the way, the talk of a “dream ticket” will spike.

Clinton fed it, not only with a primary-day suggestion that she would be “open” to a vice-presidential offer, but with a “concession” speech that contained no “concession.”

So, too, did Obama, with a victory speech that sometimes sounded as if he was placing his rival’s name in nomination.

“Senator Hillary Clinton has made history in this campaign not just because she’s a woman who has done what no woman has done before, but because she’s a leader who inspires millions of Americans with her strength, her courage, and her commitment to the causes that brought us here tonight,” Obama told his cheering supporters in St. Paul, one of the Twin Cities that gave the Democratic party and the American nation some of its greatest civil rights and social justice champions: Hubert Humphrey, Eugene McCarthy, Walter Mondale and Paul Wellstone.

“We’ve certainly had our differences over the last sixteen months,” he continued. “But as someone who’s shared a stage with her many times, I can tell you that what gets Hillary Clinton up in the morning — even in the face of tough odds — is exactly what sent her and Bill Clinton to sign up for their first campaign in Texas all those years ago; what sent her to work at the Children’s Defense Fund and made her fight for health care as First Lady; what led her to the United States Senate and fueled her barrier-breaking campaign for the presidency — an unyielding desire to improve the lives of ordinary Americans, no matter how difficult the fight may be. And you can rest assured that when we finally win the battle for universal health care in this country, she will be central to that victory. When we transform our energy policy and lift our children out of poverty, it will be because she worked to help make it happen. Our party and our country are better off because of her, and I am a better candidate for having had the honor to compete with Hillary Rodham Clinton.”

Obama finished his speech Tuesday night by talking about “the women who shattered glass ceilings; the children who braved a Selma bridge for freedom’s cause.”

History will record that the Democratic party, which in the middle passage of the 20th century committed more freely and more fully than the Republican party to freedom’s cause and the struggle to shatter those glass ceilings, began to harvest the fruits of it past commitments in the first months of 2008. It has not always been easy. It has not always been pretty. But something remarkable has begun to happen. And, on Tuesday night, as he pronounced himself to be the presumptive nominee of the Democratic party, Barack Obama was able to say, “America, this is our moment. This is our time. Our time to turn the page on the policies of the past. Our time to bring new energy and new ideas to the challenges we face. Our time to offer a new direction for the country we love.”