YORK, Pa. — John McCain and Barack Obama lumbered through the final weekend of their race for the White House amid such different circumstances from when they began that one could say they essentially have run two campaigns.

Economic upheaval and confidence malaise abound. The deep historical markers on this campaign — the first black nominee, the first female Republican running mate — have been matched by the historic challenges facing the next administration.

Obama, 47, who climbed Democratic ranks by stressing his opposition to the Iraq war, is now pounding McCain on the economy. Former Vietnam POW McCain, 72, given up as a lost cause by pundits in 2007, may need one more heroic feat. He trails Obama, the first black nominee of a major political party, in both national and key state polls.

Americans always pause after elections, but that repose will be deeper and more significant than usual Wednesday morning.

Either Obama or Alaska Gov. Sarah Palin, McCain's running mate, will be preparing to take office come January. The politics of race and gender have defined this contest from the beginning; the vote will define the country on both fronts.

"If Obama wins, I think the historical importance of the first black man being president will be understood even more than it is now," said historian Doris Kearns Goodwin. "At the time of the Iowa caucuses (10 months ago), when he won in that state, there was a sense of euphoria, I think, whether you were for him or not. There was a sense that this country had gone past something. Then it all faded as race became an issue" in the campaign itself.

Hillary Rodham Clinton's near win in the Democratic primaries and Palin's presence on the GOP ticket, Goodwin said, proved that women "have made it to that top rung" of national leadership potential.

But the world also has regressed since this marathon began.

LONGEST RACE EVER

The Dow Jones industrial average, a barometer of financial security for millions of Americans, closed at 12,580 the day before Obama announced his candidacy in February 2007. It's fallen below 9,000.

When the Illinois senator announced, he was viewed as a good story but maybe before his time. Tabloid TV took note but soon returned to its fixation on the death of Anna Nicole Smith. Clinton's advisers were predicting how many Republican women she'd attract this fall.

When McCain announced in April 2007, the "surge" of troops in Iraq was barely under way, and he was its chief defender. Debate among Democratic primary contenders was mainly about who had been right and wrong about the war.

At the time, all the talk of a woman on a national presidential ticket was on the Democratic side.

McCain first ran in 2000 and has been seeking the presidency for a good part of this decade. But he's accustomed to lengthy missions. He spent nearly six years, often under torture, in the infamous "Hanoi Hilton" and other prisons during Vietnam.

The campaign's length guaranteed a long, strange trip. A steady stream of bit players — Obama acquaintances William Ayers and the Rev. Jeremiah Wright; the ubiquitous "Joe the Plumber" — became part of bigger morality plays.

But few foresaw the momentous events that have overshadowed the campaign this fall. McCain, ahead in September polls, was scripting another miraculous survival. But his fortunes dove with the crash in the mortgage and investment markets.

The race that is about to end will be the longest and costliest ever — more than $1 billion for the presidential candidates, $5 billion overall.

TIMING FAVORED OBAMA

Obama already has raised $600 million from more than 3 million donors, shattering all records and threatening the future of the public financing system that has defined presidential campaigns for three decades.

Obama is closing with ads showing McCain and fellow Republican President Bush, whose job approval has not topped 34 percent this year, together in a rearview mirror.

Fundamentally, the length of the campaign has helped both men, but the timing of events has helped Obama and hurt McCain.

Had the economy last year been in the shape it is today, John Edwards' populist economic message might have carried him to the nomination. Timing spared Democrats a disaster. Edwards' marital infidelity became widely reported after the Democratic primaries.

Clinton, who got traction with an economic populist message too late for her to catch Obama, may have buried her less-experienced opponent had these economic problems become clearer 10 months ago.

But they did not. And Obama's grassroots organization won the Iowa caucuses. The state's overwhelmingly white caucus-goers propelled him into national prominence.

"Timing is everything," said Dianne Bystrom, head of the Carrie Chapman Catt Center on Women and Politics at Iowa State University. "(Obama) had a great organization and a message that resonated in Iowa. (At the time of the caucuses) the No. 1 issue in Iowa was the war in Iraq, and it was not the No. 1 issue in the rest of the country.

"One of the things that we always get dinged for is that we are not a diverse state," Bystrom said, referring to criticism of Iowa's first-in-line tradition. "But the fact that Iowans supported an African-American president says a lot about Iowa."

After Iowa, the primary campaign took a different tone. Some Democrats said President Clinton attempted to use race to diminish Obama's early appeal. But this fall, both Clintons closed ranks and stumped furiously for Obama.

Early in the long campaign, McCain stumbled into near oblivion. But he rebounded in New Hampshire and overwhelmed a lesser field of Republicans, including early front-runner Rudy Giuliani.

Had the economic woes become clearer last winter, former Massachusetts Gov. Mitt Romney's business-based campaign might have gained sufficient traction to prevail in the GOP field. Romney might have been a more logical running mate choice for McCain had the stock market collapsed in August, when McCain was settling on Palin.

"Certainly, if Obama wins, the length of the campaign was essential," Goodwin said. "It made people become gradually familiar with him."

Can McCain still win? Conventional wisdom is against him.

But "we seem to be in a period of where there are unprecedented and unanticipated sets of issues," presidential scholar Charles Jones said.

And if anyone has seen darkness right before dawn, it's John McCain.