The 2012 U.S. election battle between President Barack Obama and Republican challenger Mitt Romney has been one of the most expensive, acrimonious and closely contested White House races in recent memory.

As the candidates settle in for a frantic final day on the stump, here’s a look at some of the key facts and numbers from the campaign.

The final push

Obama is spending the last day of the campaign addressing crowds in Aurora, Colo., Madison, Wis., Columbus, Oh., and Des Moines, Iowa. He’ll get be getting big-time assistance from legendary rocker Bruce Springsteen, who will join him in Madison, Columbus and Des Moines. Rapper Jay-Z will be on hand to perform in Columbus.

Romney’s itinerary is even more frenetic. He starts the day in Sanford, Fla., before racing through the cities of Lynchburg, Richmond and Fairfax in Virginia to Columbus, Oh., where he will be joined by southern rockers the Marshall Tucker Band. He’ll finish campaigning in Manchester, N.H., where he will get musical support from singer Kid Rock.

Carbon footprint

Calculating the distance strictly as the crow flies between the major local airports, the two presidential candidates will rack up remarkably similar flight distances today. Obama will fly at least 2,882 kilometres and Romney will log 2,791 km in the air.

According to CarbonNeutralCalculator.com, which assumes an economy-class ticket on a commercial airliner, the minimum carbon footprint for Obama's air travel today is 457 kilograms of carbon equivalent, and for Romney it's 440 kg. (Of course, the final tally will likely be higher since the candidates won't be flying economy.)

U.S. polls

Back in the summer, Obama was expected to win the election handily. But Romney has battled back to the point where the two men are largely deadlocked.

Here’s a sampling of the latest polls on the morning of the final day of campaigning:

  • CNN: Obama and Romney tied at 49 per cent
  • Pew Research Center: Obama 48 per cent, Romney 45 per cent
  • Politico/George Washington University: Tied at 48 per cent
  • NBC News/Wall Street Journal: Obama 48 per cent, Romney 47 per cent
  • ABC News/Washington Post: Obama 49 per cent, Romney 48 per cent

World poll

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Mitt Romney greets supporters in Newport News, Va. (AP Photo/Charles Dharapak)

If the U.S. vote were open to non-Americans, Obama would be the resounding winner. A 21-country survey done by GlobeScan/PIPA for the BBC World Service showed that given the choice between the current president and Romney, most people would vote Obama. France is the most fervently pro-Obama, with 72 per cent saying they want him to be re-elected, followed by Australia (67 per cent), Canada (66 per cent), Nigeria (66 per cent) and Britain (65 per cent). Of the nations polled, only Pakistan favoured Romney (14 per cent) over Obama (11 per cent), with the vast majority (75 per cent) expressing no opinion.

Ohio: The holy grail

No Republican has ever won the presidency without first taking the swing state of Ohio. It’s no surprise then that Ohio’s 18 electoral college votes are highly prized, which is why Obama and Romney have visited the state more than 80 times combined during the 2012 campaign, and why both men are stopping in the capital, Columbus, on the final day before the vote.

Advance polls

According to the United States Elections Project at George Washington University, 29,915,972 Americans had voted early (as of Nov. 4) in 34 states and the District of Columbia.

Economic outlook

Despite heated talk about foreign policy and women's issues, the most pressing issue in this campaign is undoubtedly the economy.

As a snapshot of the economic situation before and after Obama’s first term, here’s a comparison of the key corporate indexes on the last day of the 2008 and 2012 presidential campaigns.

Dow Jones 

Nov. 3, 2008: 9,326.04

Nov. 5, 2012: 13,092.28

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President Barack Obama waves from Air Force One after touring Atlantic City, N.J., in the wake of Superstorm Sandy. (AP Photo/Patrick Semansky)

S+P 

Nov. 3, 2008: 968.67

Nov. 5, 2012: 1,414.02

NASDAQ 

Nov. 3, 2008: 1,718.89

Nov. 5, 2012: 2,983.00 

Campaign spending

According to OpenSecrets.org, as of Oct. 17, the two campaigns had spent a combined $2 billion promoting their respective candidate.

Obama's immediate campaign team spent over $540 million, the party spent $263 million and Democrat-friendly political action committees (known as "super PACs") chipped in another $127 million, for a total of $931,471,420.

On the Republican side, Romney's team spent $336,399,297, the party spent $284,156,290 and pro-Republican super PACs supplied $402,198,146, for a total of $1,022,753,733.

An analysis by the Center for Public Integrity and the Center for Responsive Politics shows that companies have contributed roughly $75 million to super PACs. Of that amount, 85 per cent of the money went to Republican-friendly groups, 11 per cent to Democratic groups and the remainder to independent organizations.

TV ad blitz

The two candidates, their party committees and supporting interest groups ran 1,015,615 television ads from June 1 to Oct. 29, based on numbers supplied by the Wesleyan Media Project.

According to the Pittsburgh Post-Gazette, the Romney campaign spent $10 million on TV ads in the last weekend of the campaign in Pennsylvania alone, while the Obama campaign spent $3 million.

The Washington Post says that as of Oct. 30, Team Obama had spent $347 million on total television ads, while Team Romney had spent $386 million. The most TV-ad money has been spent in Florida, Virginia and Ohio.