For most folks, this is just another Tuesday. But in the world of politics, this is Super Tuesday, the biggest day of balloting in the 2016 presidential race.
Voters in a dozen states will turn out for primaries and caucuses, allotting a generous share of the delegates who will decide which candidates carry the Democratic and Republican banners into the fall campaign.
Hillary Clinton and Donald Trump, the Democratic and GOP front-runners, respectively, are poised for big nights. They start out with a considerable advantage, each having won three of the first four contests.
The polls start closing at 4 p.m. Pacific time, and results will roll in East to West throughout the night and, depending on how the counting goes, into early Wednesday.
Here are five things to watch for:
• Can Sen. Bernie Sanders of Vermont significantly cut Clinton's delegate lead? The two candidates are not all that far apart in their share of pledged delegates. But Clinton opens up a huge advantage when adding in the "super delegates," or party leaders, who have given the former secretary of State their support.
If Clinton leads by 100 or more delegates after Tuesday, it will be exceedingly difficult for Sanders to overtake her in the remaining contests, because Democrats award their delegates on a proportional, rather than winner-take-all, basis. He may stay in the race for some time. But his only hope of wresting the nomination from Clinton would be one blowout win after another, which seems unlikely.
• Can Sanders break through among black voters? Seven of the Super Tuesday contests will take place in the South, in states with substantial African American populations. In her crushing South Carolina victory Saturday, Clinton won the votes of nearly 9 in 10 black voters. Some of the earliest returns Tuesday will come from Alabama, Arkansas, Georgia and Virginia. The results in those states, and exit polls giving an insight into the black vote, will indicate what kind of night it's going to be for Sanders and Clinton.
Beyond that, it could also signal the candidates' respective strength heading into future contests, including primaries in Illinois, Michigan and Ohio, where the African American vote will be significant.
• Trump leads the polls in all the biggest contests save Texas, where Sen. Ted Cruz is favored to carry his home state. The question is whether two other rivals, Sen. Marco Rubio of Florida and Ohio Gov. John Kasich, can avoid a Super Tuesday shutout. Both their strategies are predicated on surviving Tuesday and winning once the race gets to their respective home states for winner-take-all contests on March 15. A big Trump win Tuesday would not only pad his already substantial delegate lead but also raise serious doubts about the viability of Rubio and Kasich, who have yet to win a state.
• If they lose to Trump, can his rivals at least keep it somewhat close? Several states, including Texas and Georgia, require candidates to win a minimum of 20% of the vote to qualify for delegates. "My big question is, do other candidates add up to more or less delegates than Trump?" said David Wasserman, a campaign analyst with the nonpartisan Cook Political Report. "If more, odds of a contested convention increase."
• Whither Ted Cruz? If he fails to win Texas, his campaign is finished. But how does he fare among evangelical voters elsewhere across the South, the most religious part of the country? Christian conservatives powered Cruz to victory in the Iowa caucuses, Trump's only defeat. Since then, however, evangelical voters have favored the businessman over the senator, despite Cruz's explicit appeals and consistently conservative stance on issues such as abortion and same-sex marriage. Take away that base of support and Cruz is left with very little.