The big day is finally here — after tonight's Super Tuesday results, there will be a much clearer picture of how both the Republican and Democratic races could shake out. Will Donald Trump continue his dominance? Can Marco Rubio catch up? Can Ted Cruz rebound? Will Hillary Clinton roll through the South? Can Bernie Sanders bounce back after a devastating South Carolina loss?

More than a dozen states are voting today — some in primaries, some in caucuses whose results may not be known for quite a while. A total of 1,460 delegates are up for grabs — 865 for Democrats, 595 for Republicans.

And remember — margins matter in these contests. They're not winner-take-all, and closer finishes impact the number of delegates awarded on a state-by-state basis.

It's a lot to follow, so here are some of the most important states to watch.

Texas

The Lone Star State is the crown jewel of the evening, with the most delegates up for grabs. Republicans will allocate 155 delegates, while there are 222 for the Democrats.

It's the home state of Sen. Ted Cruz, and expectations are sky high for the Republican. Polls have shown him leading, but Trump is on his heels. If the real estate mogul somehow pulls off an upset or if Cruz escapes with just a narrow win, it could be the senator's end of the road. It's been a month since Cruz's win in Iowa, but that's a lifetime in politics. Third-place finishes in South Carolina, where he once had strength, and in Nevada can't sustain him.

On the Democratic side, Clinton is looking to make a statement over Sanders. Polls show her with more than a 20-point lead.

Georgia

The Peach State has the second-largest number of delegates up on Tuesday — 76 for Republicans and 102 pledged delegates for Democrats. It also will be an important early barometer for whether there's been a shift in the GOP race. Trump still leads polls here, but Rubio has made a late push in the state, campaigning there on Monday morning (even as he had lost his voice). His strong debate performance last week could lift him here — remember, it's Rubio who's often been the beneficiary of late-deciding voters, according to exit polls in Nevada and South Carolina. An NBC/Marist poll gave Trump just a 7-point edge, narrower than other surveys. Metro Atlanta will make up the bulk of the primary vote, and if Trump is winning in the more conservative, rural areas of the state, he'll have a good night.

Like South Carolina, Georgia's Democratic primary is expected to have high African-American turnout, which could again bode well for Clinton. In recent polls, she has more than double the support of Sanders. In 2008, 52 percent of the Georgia electorate was black.

Tennessee

Rubio has gotten a surge of late support from some top officials here, nabbing endorsements from both Gov. Bill Haslam and Sen. Lamar Alexander. Polls show Trump still has an advantage, and since more than a quarter of the vote is expected to come from early voting, any momentum for Rubio may be blunted. Eastern Tennessee is the most conservative part of the state — if either Rubio or Cruz are breaking away there, it could be closer than expected.

Clinton is expected to carry the Democratic primary easily. There's still a lot of goodwill for the Clintons in the Volunteer State, which borders Arkansas. Bill Clinton was the last Democrat to carry the state in a presidential race (and Al Gore's inability to carry his home state in 2000 cost him the election). Polls show Hillary Clinton with more than a 2-to-1 lead over Sanders.

Alabama

Trump's dominance in this state got a boost over the weekend when he secured the endorsement of Alabama Sen. Jeff Sessions — a major blow to Cruz, who has yet to receive an endorsement from any of his fellow senators. This is a state where Cruz should be doing well. In 2012, 80 percent of the GOP primary electorate described themselves as evangelical voters. Yet Trump leads among born-again voters in polls, and he has a massive lead in the state. A good night for either Cruz or Rubio here might be just holding Trump to less than a 20-point victory.

Alabama is another Southern state with a high African-American population where Clinton is expected to cruise to victory over Sanders. A Monmouth University poll released Monday gave her a nearly 50-point edge, similar to her margin of victory in South Carolina this weekend.

Virginia

If there's one place where Rubio could pull off an upset over Trump on Tuesday, the Old Dominion might be it. The most recent polls still give the GOP front-runner a double-digit lead, but Rubio has been focused heavily on the commonwealth and campaigned all day in Virginia on Sunday. Watch the more moderate, highly educated D.C. suburbs and exurbs for hints on who might emerge as the victor. If Rubio is pulling big margins here, it could be a surprising finish.

Polls also give Clinton an edge in Virginia. The state's governor, Terry McAuliffe, has been a longtime friend and confidante to the Clintons.

Arkansas

The Natural State is one place where Cruz could have a stronger-than-expected night. There's been scant polling in the state, but one survey done at the beginning of February gave the senator from neighboring Texas a narrow advantage over Trump and Rubio, who were neck-and-neck.

As for Clinton, she should easily win in the state that launched her and her husband's political careers.

Massachusetts

This northeast state is tailor-made for someone like Trump, who won big in neighboring New Hampshire three weeks ago. He has a decisive lead here as well, according to recent polls. Ohio Gov. John Kasich, who has been looking toward later contests such as his home state and Michigan, could make a strong showing in the Bay State, battling with Rubio for the state's more moderate GOP electorate.

For Democrats, this one could be a nailbiter. Sanders doesn't enjoy the huge advantage he had in the Granite State, and polls show it's a close contest between him and Clinton.

Oklahoma

Trump's lead in polls is smaller in this state than it is in many Southern contests. Rubio has the backing of Oklahoma Sen. Jim Inhofe and the state's popular former Sen. Tom Coburn, who closed out a rally for him on the eve of Super Tuesday. Cruz has been neck-and-neck with Rubio for second, too, and this really could be a three-man contest.

As the Democratic contests also move out of the South, Clinton and Sanders are running close in the state.

Minnesota

There's been no recent poll in this state, where two-hour caucuses will be held Tuesday night. The Upshot blog in The New York Timespredicted this could be a surprisingly strong state for Rubio, where lower turnout is expected and more moderate voters could be the ones to show up.

For Democrats, Sanders has made a late push in the state. He actually spent Saturday night campaigning in Minneapolis instead of waiting in South Carolina for results — a good choice given Clinton's resounding win. But when he landed he learned the state's largest paper, the Minneapolis StarTribune, had endorsed his opponent. He has an urgent need to do well here, and Sanders has made three stops in the state in the past four days.

Colorado

Sanders needs a victory somewhere on Tuesday night outside of Clinton's Southern stronghold and his home state of Vermont, and Colorado is another place to watch to see if he gets it. He's drawn big crowds in recent visits to the state, but the caucuses are tough to predict.

On the Republican side, don't wait up — there won't be an immediate apparent winner. There are only meetings throughout the state to pick delegates to county caucuses; there's no presidential preference poll that is happening.

Vermont

There's no suspense on the Democratic side: The home state favorite Sanders will mop up big here.

Given that the state's electorate is similar to New Hampshire, on the GOP side it's Trump who probably has an edge in the race for the state's 16 Republican delegates.

Copyright 2021 NPR. To see more, visit https://www.npr.org.