Ten states' delegates are up for grabs on March 6: Alaska, Georgia, Idaho, Massachusetts, North Dakota, Ohio, Oklahoma, Tennessee, Vermont and Virginia.
The primary and caucus system in some states will award delegates in proportion to each candidate's number of votes or give the top candidate all of them in a winner-take-all system in others.
Either way, the delegates each candidate wins on Super Tuesday are bound to support their candidate, at least on the first ballot, at the convention.
After a grueling 26 debates and 13 caucuses and primaries, Super Tuesday may seem as though it won't make much difference in this year's notoriously back-and-forth race, no matter how many states are up for grabs.
But a look back at Super Tuesday history proves just how important the mega-contest can be. Here are five reasons every voter in America should be watching Super Tuesday and five possible outcomes in 2012, based on past contests within both parties.
1. 1984: Start of Super Tuesday
Super Tuesday was basically designed to nationalize the message, to try to reduce the influence of the so-called Iowa syndrome, Sen. Chuck Robb of Virginia said in 1988.
Super Tuesday was and is meant to determine whether a candidate is able to appeal to voters on a national level, not just by stumping regional issues tailored to each state. It was also meant to make the race more about endurance than momentum, with the worthiest candidates selected not by the first states to cast votes but by a bloc of states rendering a verdict simultaneously.
The idea of Super Tuesday was born in 1984, when the primary season actually featured three super contests meant to act as a sink-or-swim moment for the Democrats challenging President Ronald Reagan.
Candidates Walter Mondale, Gary Hart and Jesse Jackson were forced to address not only social issues and the state of specific industries within the U.S. economy, but broader topics such as foreign policy, tax policy and the possibility of war overseas.
The three contests shifted voter support from Jackson, whose off-the-cuff remarks frequently caused controversy, and Hart, who had been leading as the fresher, more moderate candidate, to Mondale, whose rips on Hart's New Ideas compounded with Hart's own gaffes helped propel the then-vice president to the Democratic nomination.
It wasn't until 1988, however, that Super Tuesday became what it is today, with nine Southern state primaries determining the front-runner for both the Republican and Democratic nominations.
Since then, the contest has been spread across states from every region, and has come late enough in the race that a final push by the candidates should reveal the likely nominee.
Super Tuesday's origins are particularly important to Santorum and Gingrich in 2012.
Although Romney has so far been unable to claim the title of undisputed front-runner, he remains the candidate with the most delegates (203) and most victories so far. More importantly, however, the states he has won aren't very diverse, geographically of socioeconomically - Nevada, Florida, Michigan, New Hampshire.
Paul, meanwhile, continues to rely on his strategy for picking up delegates through the caucus system by stressing universal themes like cutting the budget and bringing the troops home, a strategy that should continue to help him on March 6.
Santorum, however, has secured his wins largely through a reliance on social issues like abortion and gay marriage, topics that have less power on the national stage. For Gingrich, with only South Carolina to his name, winning a couple of Southern states won't do him much good if the former speaker and Georgia congressman can't prove he has a national appeal, as well.
2. 1992: Remembering The Clinton Comeback
During the aftermath of the Gulf War, President George H.W. Bush had approval ratings as high as 89 percent, making Democrats anxious to secure a candidate who could win back the White House in 1992.
In 1991, that candidate was not Bill Clinton. At the Iowa caucus, Clinton finished a distant third, and though news outlets were already calling him the Comeback Kid after reports of an affair with Gennifer Flowers failed to derail his campaign, it still seemed unlikely the Arkansas governor would secure the nomination.
On March 10, however, Clinton shocked naysayers by not only sweeping the South but securing two top prizes in Florida and Texas. After coming back from the dead, Clinton set his sights on winning New York to secure a victory outside his native South. His landslide win transformed him into the consensus candidate, and gave him the momentum to take on President Bush as the incumbent's foreign-policy wave began to ebb.
Fewer Southern states are on the ballot in 2012, depriving Gingrich of the chance to garner at least the appearance of consensus. Nonetheless, the real lesson from the Clinton comeback is how important Super Tuesday can be for changing an uncertain campaign.
This year, the status of front-runner has spun wildly from candidates as different from each other as Romney and Gingrich to Herman Cain and Santorum.
If one candidate emerges the clear winner after Super Tuesday, it's possible that voters will be so exhausted by the nomination process that the candidate, regardless of past primaries, will become the presumptive Republican nominee.
3. 2000: Eliminating the Surplus
Just as a sweeping victory on Super Tuesday can lock up a candidate's party nomination, failing to make an impact is an almost certain death knell for any hopeful in the race.
In 2000, both the Republican and Democratic parties found themselves with one front-runner and one alternate candidate (who wins just enough votes to remain a plausible threat in the primaries). For Republicans, the choice was between George W. Bush and John McCain; for Democrats, it was Al Gore and Bill Bradley.
After two Super Tuesday contests in March, however, both McCain and Bradley were finished, with Bush and Gore the undisputed and almost unanimously supported nominees, an indicator of the tight presidential race ahead.
McCain dropped out after winning only four of the 13 states up for the Republican primaries on March 7, and Bradley withdrew after failing to win a single state by Super Tuesday's second round a week later.
All of the 2012 Republican candidates except Paul have managed to win at least one state's primary or caucus. If Paul fails to net enough delegates, his legitimacy as a national candidate will be in jeopardy. His position, however, isn't nearly as precarious as that of Gingrich, who doesn't have the grass-roots support Paul does. If the former House of Representatives speaker fails to win more than Georgia, his lack of impact will speak as loudly as the other candidates' victories.
4. 2004-2008: How 'Mini-Tuesdays' Changed The Game
When it came time for President's Bush re-election campaign, several states decided to move their primaries before Super Tuesday on Feb. 3, 2004, in an attempt to make their states count for more after the massive contest. Five states ended up holding primaries beforehand, with two other states hosting caucuses, convinced that holding contests after Super Tuesday would greatly diminish their importance.
By 2008, the rush to keep their state important meant that a record 24 states, with half the delegates up for grabs, were all scheduled for Feb. 5, the largest Super Tuesday to date.
Super Duper Tuesday dwarfed the originally scheduled Super Tuesday on March 4, which was left with only four states holding elections. As one pundit wrote: This year ... Super Tuesday isn't so super. In the end, having so many states on the line in an already tight race just ended up splitting the election more, with Hillary Clinton slightly ahead in delegates and wins but still losing the nomination to Barack Obama.
After that election, those organizing the 2012 Republican primaries were careful to set up several mini-Tuesdays before and after Super Tuesday, on Feb. 7 and throughout April and May. States that have tried to move their primaries or caucuses early, like Florida and New Hampshire, have had their delegate numbers reduced by the RNC.
As a result, only 10 states will be up for grabs this Super Tuesday, meaning March 6 is more important on a symbolic, rather than delegate-driven, level. Though a clear winner for Super Tuesday, as noted, could end up making the rest of the race less important, the most likely outcome is two or at most three contestants emerging from the contest to battle it out in states such as Wisconsin, Texas and California this spring.
5. Present-Day Lessons: Still All About Ohio
Ohio has been one of the most important states in the primary season even before Super Tuesday began, and this year, the swing state's status as a predictor of the outcome of the Republican National Convention has become crucial.
Historically, the candidate who wins the Ohio primary usually goes on to win the nomination, and almost every nominee who wins the state in the general election becomes the next president. This has been especially true within the GOP. It was the case with Ronald Reagan in 1980 and 1984, George H.W. Bush in 1988, George W. Bush in 2000 and 2004, and John McCain in the 2008 primary season.
Of the state elections on March 6, only Georgia has more Super Tuesday delegates to offer. More importantly, however, the candidates most likely to benefit in the state are those who can both appeal to blue-collar families and have enough money and organization to beat out rivals scrambling for every vote.
In 2012, Santorum definitely has the advantage there over Romney, as does Paul (though to a lesser extent). The former Massachusetts governor still doesn't resonate with families earning between $20,000 and 75,000 a year, and his notable faux pas involving his wealth haven't helped matters in recent weeks.
In terms of organizational power, however, Romney has all the other candidates beat. It was that edge that gave him his barely-there victory over Santorum in Michigan, and what will give him the chance to influence voters up to the moment they enter the voting booth.
If Romney wins Ohio, he'll appear invincible. If he doesn't, Super Tuesday history shows that a sudden comeback or a split race can make all the difference in the world.