Five Northeastern states will cast their primary ballots today. Trump is coming off a major victory in New York—and Pennsylvania offers not only the most delegates but also Trump’s biggest challenge for Super Tuesday 3.0. Here’s the top five things you need to know as you follow the Pennsylvania primaries.

On the Republican side, there are a lot of unbound delegates up for grabs.

The GOP candidate who gets the popular vote statewide will win 17 delegates bound to vote for him on the first ballot at the Republican convention. The remaining 54 delegates—three per congressional district—are unbound and can vote for anyone they want during the first ballot, though many have said they’ll support whoever wins the popular vote in their district.

The political divides within the Pennsylvania GOP fall along geographical lines.

Kasich’s best shot is in Philadelphia and the suburbs, where there are a lot of moderates. Trump’s stronghold is in northern Pennsylvania, known for its blue-collar conservatives. Cruz will be a natural pick for voters in the center of the state, where social-conservative voters abound.

Trump’s polling is strong, but Cruz may surprise.

The Real Clear Politics average has Trump up by nearly 22 points among Pennsylvania voters. Since they’ll be choosing three delegates for each district, both the Cruz and Trump campaigns have been publicizing their preferred slates. Cruz’s ground game is strong as usual, and it’s a two-pronged strategy. In addition to voter outreach, Cruz has been meeting with candidates for delegates before they’re even elected in an attempt to win their support, says Nathan Benefield, vice president of policy at the Commonwealth Foundation, a Pennsylvania free-market think tank.

The Democratic side is much more straightforward—and likely a sweep for Clinton

Pennsylvania will send 210 delegates to the Democratic National Convention. Hillary Clinton, who is leading by 16 percent in the Real Clear Politics average, stands to win 189 pledged delegates. Superdelegates account for the remaining 21, chosen by the Democratic party, which is also likely to favor Clinton over Sanders.

Tiffany Trump will be voting in Philadelphia.

Like New York, Pennsylvania has a closed primary system. To cast their ballots in today’s primaries, voters needed to register in Pennsylvania by March 28. Ivanka Trump may have bungled her New York voter registration, but the Donald’s youngest daughter, a senior at the University of Pennsylvania, has been a dutifully registered Republican in the state since 2012.

— Jillian Kay Melchior writes for Heat Street and is a fellow for the Independent Women’s Forum and the Steamboat Institute.