TRENTON -- It's a routine that happens every four years: Tens of thousands of people gather in a major American city for the Republican National Convention, where the party officially crowns its presidential nominee.

But this year's convention is anything but routine, with presumptive GOP nominee Donald Trump's candidacy threatening to tear the party in half.

"We haven't had this kind of contentiousness at a Republican convention in a generation," said Ben Dworkin, a political science professor at Rider University.

Here is a look at why you should care about the 2016 edition, which runs Monday through Thursday in Cleveland.

1. The Grand Old Party is divided -- and it's unclear what will happen.

Trump plowed through 16 opponents -- including New Jersey Gov. Chris Christie -- to win the GOP primary. But his unconventional campaign and controversial rhetoric has turned off a string of mainstream Republicans. Some have vowed not to support the celebrity businessman and former Atlantic City casino tycoon even as he prepares to face presumptive Democratic nominee Hillary Clinton in November.

In fact, only one of the five living former GOP presidential nominees is scheduled to attend the convention: Bob Dole.

"I think that's just incredible," said Patrick Murray, director of the Monmouth University Polling Institute. "The number of establishment Republicans who are avoiding Cleveland like the plague is unheard of."

The convention could be a chance to unify the party. But Krista Jenkins, a political science professor at Fairleigh Dickinson University, said there are still many unknowns.

"It's potentially American political history being made," Jenkins said.

2. Some are trying to stop Trump.

Though he won the Republican primary a month ago, Trump won't officially be named the nominee until Thursday. But a number of anti-Trump Republicans are staging an effort to change the rules and force a floor fight to deny him the nomination and replace him with someone else. One of the leaders of the movement is New Jersey politician Steve Lonegan.

Experts say it's a longshot. "A tiny, tiny shot," said Larry Sabato, a political science professor at the University of Virginia. "Total chaos isn't an attractive alternative to Trump."

3. Trump will speak in prime time.

The real estate mogul is scheduled to speak next Thursday night after accepting the party's nomination. It will give him a chance to address millions of network television viewers in primetime. And it will likely bring the kind of ratings he helped draw during the GOP debates.

There will also be other speakers throughout the week, though a lineup hasn't been reveled. Ted Cruz, Paul Ryan, Scott Waker, and legendary college basketball coach Bobby Knight are all expected to speak, according to reports.

4. The party will unveil its platform.

Republican leaders also hash out the party's views in a platform every convention. The question this year is: What will it look like with Trump as the nominee?

Sabato said there will likely "less free trade," and the party will be tougher on immigration" and "maybe less harsh toward gay rights."

"But President Trump isn't likely to pay much heed to the wording of the platform," the professor added.

Murray said the convention could "signal a wholesale change in what Republican party stands for."

5. There is a threat of violence.

Protestors have been common at both parties' conventions throughout the years. And experts expect many to fill the streets of Cleveland next week.

But the worry is whether it will turn violent. Trump has suggested there could be "riots" if he's denied the nomination. And his rallies have often seen fighting break out between protestors and supporters.

Could it be a repeat of the violence that broke out at the 1968 Democratic National Convention?

"I doubt the likely disruption is anything close to the enormous scale we saw in 1968," Sabato said.

Brent Johnson may be reached at bjohnson@njadvancemedia.com. Follow him on Twitter @johnsb01. Find NJ.com Politics on Facebook.