And now ABC also projects that Haley will win Vermont. The race remains super close, however, and it’s not yet clear how delegates will be awarded.

—Monica Potts, 538

Polls have now closed in California, where all parties run on a single primary ballot (other than in presidential races). Unfortunately, neither party is particularly popular in the state. According to a February survey from the Public Policy Institute of California, likely primary voters in California don’t have a favorable view of either political party: The Democratic party is underwater by 10 percentage points, with 44 percent of likely voters saying they have a favorable impression of the party and 54 percent saying they have an unfavorable view. The Republican party fares even worse, with a net favorability of -55 points, 22 percent favorable and 77 percent unfavorable.

—Mary Radcliffe, 538

The New York Times and the Associated Press have projected that Haley will win the Republican primary in Vermont, making it the second win for her after Washington, D.C. (ABC News has not yet made a projection in this race.)

While Trump remains ahead on the delegate count, the win could give some juice to her campaign. She's vowed to stay in because she says that Trump and Biden are both too old and out of touch, and she has been capturing a sizable minority of primary voters who are unhappy with the former president in many states across the country. Still, she'll need to get a majority of the final vote to take all of the delegates, and that remains up in the air. With 92 percent of the expected vote in, she has 49.7 percent to Trump's 46 percent. If neither candidate reaches 50.1 percent, they'll split the state's delegates.

—Monica Potts, 538

North Carolina’s 13th District is yet another Democratic-held seat that North Carolina Republicans redrew this year to be safely red. Unsurprisingly, the GOP primary attracted a wide field, and with 67 percent of the expected vote counted according to the Associated Press, attorney Kelly Daughtry is in first place with 29 percent, followed by former federal prosecutor Brad Knott with 18 percent, businessman DeVan Barbour with 17 percent and yet another businessman Fred Von Canon with 16 percent. As a reminder, if no one gets 30 percent, the runner-up is entitled to request a runoff.

—Nathaniel Rakich, 538

Super Tuesday has over 40 years of history that are deeply entwined with a bunch of issues in the presidential nomination process. The term "Super Tuesday" was first used in 1980 but was promoted by Democrats in 1988 as a deliberate effort to give an advantage to more moderate candidates. This was a direct reaction to the idea that the party's 1984 nominee, Walter Mondale, had lost to Ronald Reagan because he was too liberal. This strategy didn't really work out, though, and Democrats ended up nominating another northern liberal, Michael Dukakis.

In other words, this early attempt at a Super Tuesday brought some of the disadvantages of a regional primary, reducing the amount of attention on individual states and pressuring states to move their primaries earlier without really strengthening the influence of the region. Another drawback was that, by trying to enhance Southern influence by holding contests early, Super Tuesday also contributed to the "front-loading" problem", or the issue of having too many delegates selected at the beginning of the primary calendar.

Over time, Super Tuesday has taken on other significance as an important turning point in the race. As party politics scholar Caitlin Jewitt noted, in 2016, everyone thought that Sen. Ted Cruz needed to do well on Super Tuesday, which was heavily concentrated in Southern states where he needed to rack up wins — and when that didn't happen, it was a significant blow to his candidacy. For Biden in 2020, Super Tuesday marked the point when the party consolidated behind him. And in 2008, Super Tuesday made it clear that the Democratic nomination was a real race between Hillary Clinton and Barack Obama, as neither one scored a decisive victory.

It's hard to know exactly how this will play out in 2024. Republicans don't have the same ideological history with the big primary day as Democrats do. But the potential for a turning point in the race is there: Because so many delegates are at stake today, unless Haley wins a significant share of them, it may not make sense for her to stay in the race after tonight.

—Julia Azari, 538 contributor