Now it’s history.

In a sweeping mandate for political change that ended the longest and most expensive presidential race ever, record numbers of Americans swarmed polling places Tuesday and chose Democrat Barack Obama of Illinois by a wide margin as the next president of the United States.

His opponent, Republican Sen. John McCain, conceded the election shortly after 11 p.m. ET.

Obama, the first African American candidate to head a major political party ticket, will take office on January 20, 2009.

By some estimates, more than 130 million voters helped decide an election that began nearly two years ago primarily as a debate over the six-year-old war in Iraq, but ended as a referendum on the battered U.S. economy.

The president-elect will take the helm at perhaps the most turbulent period in American history since the start of the Great Depression.

The deciding 270th electoral vote fell into Obama’s column just before 11 p.m. ET when Fox News projected that Obama would win California and with it 55 Electoral College votes, more than enough to ensure his victory.

Shortly before midnight, Obama led with 338 Electoral College votes to McCain's 155 and the landslide was official. Obama emerged with his family -- wife Michelle and two daughters -- to address supporters in Chicago at 11:58 p.m. ET.

Earlier in the evening, McCain jumped out to an early lead, taking eight electoral votes in a win in Kentucky, one of the first states to close its polling stations.

But Obama soon took over the lead for good as strongly Democratic northeastern states such as Vermont and Massachusetts started reporting results.

A major turning point occurred around 8:30 p.m. EST when Pennsylvania, one of the most sought after battle ground states, fell in line for Obama and with its 21 electoral votes. Both candidates spent considerable time and resources in Pennsylvania in the days leading up to the election.

Then around 9 p.m. ET Minnesota, New Mexico, New York, Wisconsin, Rhode Island, and Michigan, were all called for Obama and McCain’s chances dwindled further. Ohio, another important swing state, and its 20 electoral votes fell for Obama about 9:15 ET.

A win in Virginia about 10:40 p.m. ET put Obama at 220, with only a victory in California standing between him and victory in the electoral college.

In a burst of optimism presumably based less on an eventual winner but more on the end of the uncertainty inherent to all presidential elections, the stock markets surged on Tuesday. The Dow Jones Industrial average rose 305 points.

Everyone from stock traders to small business owners to historians seemed relieved that it was over.

“There’s always a level of uncertainty on all national elections. Now people can move ahead with planning because they know what direction we’re heading,” said Mark S. Jaffe, chief executive officer of the Greater New York Chamber of Commerce.

Obama will succeed Republican President George W. Bush, who served eight years and whose popularity has plunged during his second term.

He will inherit from Bush the worst financial crisis since the 1930s, complex and relentless wars in Iraq and Afghanistan, a health-care system desperately in need of reform, among other issues.

The election touched a nerve nationwide and long lines greeted the throngs of voters who descended on polling stations across the country, most especially in battleground states such as Pennsylvania, Ohio and Virginia.

The first polls closed in parts of Indiana and Kentucky at 6 p.m. ET and it quickly became apparent that Obama would emerge the winner.

Polls had predicted as much for weeks, and more than one-third of U.S. eligible voters had already voted before polling stations opened on Tuesday.

The race had been a toss up through much of the summer. Obama was still essentially unknown on the national political stage and coming off a difficult victory over Sen. Hillary Clinton in the primaries, while McCain had sewn up the nomination early.

But everything changed in September, when the gradually escalating financial crisis brought on by the bursting of the U.S. housing bubble exploded in full force.

The crisis dominated the news and voters’ attention shifted swiftly from national security concerns, an issue that favored McCain and the Republicans, to the economy, which tilted toward the Democrats and Obama.

McCain was perceived to be slow in responding to the crisis and polls began to favor Obama.

McCain never recovered.

Charles Geisst, a Wall Street historian and professor of finance at Manhattan College, spoke for many when he expressed relief that the election is over. “Aren’t we all,” he said.

Geisst said Obama will have little time to celebrate his victory.

“To be optimistic would be a mistake,” he said. “By January we could be in a much worse situation than we are now.”

Consequently, many of the federal proposals aimed at propping up the sagging economy – not least a $700 billion rescue package approved by Congress in October -- could be obsolete by the time Obama is sworn in.

Geisst said Obama would be smart to delay campaign proposals aimed at raising taxes on wealthy Americans until the economic crisis has stabilized.

Meanwhile, in celebrations across the country Obama supporters took to the streets after the victory cheering the historic event that seemed all but impossible just a year ago.