This is not an endorsement. We write neither as Republicans nor Democrats, but rather as Americans.

And for all Americans, something of great significance happened this week.

A black man, a man born into the promise secured by the wrenching Civil Rights era battles of the 1950s and 1960s, has become the presumptive presidential nominee of the Democratic Party. After a hard-fought and tumultuous 17-month campaign, Illinois Sen. Barack Obama on Tuesday beat N.Y. Sen. Hillary Rodham Clinton in the delegate count and, in a speech that night, claimed the nomination of their party.

Sen. Obama has presented himself as the candidate of change. Whether the change he would promote if elected president is right or wrong for this country is an issue we will save for later reflection, after Obama and presumptive Republican nominee Sen. John McCain engage in a full-fledged campaign. Right now, though, it is important to mark how the very fact that Obama captured the nomination is itself change of historic magnitude.

For in the long view of history, it was but a moment ago that a black man in America could not be elected cemetery commissioner, let alone sheriff, mayor, governor or senator. Obama was born at the end of that era, when the sit-ins and boycotts and marches protesting Jim Crow were winding down and the de-institutionalizing of racism in America became national policy. Though the presidential nomination was by no means handed to Obama, it would have been unthinkable without the huge transformation of American politics and culture that has been undertaken -- legally, institutionally and politically -- since the 1960s.

That transformation aided Hillary Clinton in her historic quest for the presidency as well. Much of what can be said about the precedent-setting nature of Obama's nomination can also be said for women in American politics, who likewise were proscribed until recently from meaningful political participation. Hillary Clinton got closer to a major-party presidential nomination than any woman in American history and it was fitting that Obama honored her for that in his Tuesday night speech.

Obama and Clinton are, despite their long competition, fellow pathbreakers in the great American journey toward equality. Perhaps the most compelling measure of how far we have come is that while Americans over the age of 50, say, are still shaking their heads at the wonder of a woman and a black man battling it out for the Democratic party presidential nomination, college students and many of those under 50 don't see what all the fuss is about. They're not jaded, mind you, they've just come of age in a different era.

The pundits, ever eager to parse the tiniest and, ultimately, least consequential moments of this long campaign, are now dwelling on Clinton's combative Tuesday night speech in which she did not concede the nomination. It's a shame that Clinton hasn't found a graceful way to give up, and her petulance was matched in equal measure by Obama's graciousness.

Whether Obama chooses Clinton as his running mate is a matter for his campaign and party to decide. As that gets hashed out by the Democrats, we are looking forward to the next stage in what already seems like the world's longest presidential campaign. That's the contest -- finally -- between two candidates, Obama and McCain, who represent what is best about this country.

McCain, a longtime senator, decorated veteran and former prisoner-of-war, has a strong independent streak that's led him to buck his party over significant issues in the past. He will likely prove a lively match for Obama, whose resume is shorter, but whose ambition, intelligence and eloquence have combined in powerful synergy.

So: On to November.